Tissue modification devices

ABSTRACT

Described herein are elongate devices for modifying tissue having a plurality of flexibly connected and rungs or links, and methods of using them, including methods of using them to decompress stenotic spinal tissue. These devices may be included as part of a system for modifying tissue. In general, these devices include a plurality of blades positioned on for formed from) rungs that are flexibly connected and may be separated by one or more spacers. The rungs are typically wider than they are long (e.g., rectangular). The rungs may be arranged, ladder like, and may be connected by a flexible connector substrate or between two or more cables. Different sized rungs may be used, or rungs with different cutting properties. In some variations the tissue modification devices may have a non-linear axial shape, or may be converted from a first axial shape to a second axial shape.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/US2009/050492, filed on Jul. 14, 2009, published as WO2010/009093, which claims priority to U.S. Provisional PatentApplication No. 61/080,647, filed on Jul. 14, 2008; U.S. ProvisionalPatent Application No. 61/081,685, filed on Jul. 17, 2008; and U.S.Provisional Patent Application 61/163,699, filed on Mar. 26, 2009, eachof which are herein incorporated by reference in their entirety.

This application is also a continuation-in-part of U.S. patentapplication Ser. No. 12/324,147, filed on Nov. 26, 2008, published as2009/0149865, which claims priority to U.S. Provisional PatentApplication No. 61/080,647, filed on Jul. 14, 2008 and U.S. ProvisionalPatent Application No. 61/081,685, filed on Jul. 17, 2008, each of whichare herein incorporated by reference in their entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to medical/surgical devices andmethods. More specifically, the present invention relates to flexibletissue modification devices and methods of modifying tissue using suchdevices, particularly for treatment of spinal stenosis.

BACKGROUND OF THE INVENTION

A significant number of surgical procedures involve modifying tissue ina patient's body, such as by removing, cutting, shaving, abrading,shrinking, ablating or otherwise modifying tissue. Minimally invasive(or “less invasive”) surgical procedures often involve modifying tissuethrough one or more small incisions or percutaneous access, and thus maybe more technically challenging procedures. Some of the challenges ofminimally invasive tissue modification procedures include working in asmaller operating field, working with smaller devices, and trying tooperate with reduced or even no direct visualization of the tissue (ortissues) being modified. For example, using arthroscopic surgicaltechniques for repairing joints such as the knee or the shoulder, it maybe quite challenging to modify certain tissues to achieve a desiredresult, due to the required small size of arthroscopic instruments, theconfined surgical space of the joint, lack of direct visualization ofthe surgical space, and the like. It may be particularly challenging insome surgical procedures, for example, to cut or contour bone orligamentous tissue with currently available minimally invasive tools andtechniques. For example, trying to shave a thin slice of bone off acurved bony surface, using a small-diameter tool in a confined spacewith little or no ability to see the surface being cut, as may berequired in some procedures, may be incredibly challenging or evenimpossible using currently available devices.

One area of surgery which would likely benefit from the development ofless invasive techniques is the treatment of spinal stenosis. Spinalstenosis occurs when nerve tissue and/or the blood vessels supplyingnerve tissue in the spine become impinged by one or more structurespressing against them, causing symptoms. The most common form of spinalstenosis occurs in the lower (or lumbar) spine and can cause severepain, numbness and/or loss of function in the lower back and/or one orboth lower limb.

FIG. 1 is a top view of a vertebra with the cauda equina (the bundle ofnerves that extends from the base of the spinal cord) shown in crosssection and two nerve roots branching from the cauda equina to exit thecentral spinal canal and extend through intervertebral foramina oneither side of the vertebra. Spinal stenosis can occur when the spinalcord, cauda equina and/or nerve root(s) are impinged by one or moretissues in the spine, such as buckled or thickened ligamentum flavum,hypertrophied facet joint (shown as superior articular processes in FIG.1), osteophytes (or “bone spurs”) on vertebrae, spondylolisthesis(sliding of one vertebra relative to an adjacent vertebra), facet jointsynovial cysts, and/or collapse, bulging or herniation of anintervertebral disc. Impingement of neural and/or neurovascular tissuein the spine by one or more of these tissues may cause pain, numbnessand/or loss of strength or mobility in one or both of a patient's lowerlimbs and/or of the patient's back.

In the United States, spinal stenosis occurs with an incidence ofbetween 4% and 6% (or more) of adults aged 50 and older and is the mostfrequent reason cited for back surgery in patients aged 60 and older.Patients suffering from spinal stenosis are typically first treated withconservative approaches such as exercise therapy, analgesics,anti-inflammatory medications, and epidural steroid injections. Whenthese conservative treatment options fail and symptoms are severe, as isfrequently the case, surgery may be required to remove impinging tissueand decompress the impinged nerve tissue.

Lumbar spinal stenosis surgery involves first making an incision in theback and stripping muscles and supporting structures away from the spineto expose the posterior aspect of the vertebral column. Thickenedligamentum flavum is then exposed by complete or partial removal of thebony arch (lamina) covering the back of the spinal canal (laminectomy orlaminotomy). In addition, the surgery often includes partial or completefacetectomy (removal of all or part of one or more facet joints), toremove impinging ligamentum flavum or bone tissue. Spinal stenosissurgery is performed under general anesthesia, and patients are usuallyadmitted to the hospital for five to seven days after surgery, with fullrecovery from surgery requiring between six weeks and three months. Manypatients need extended therapy at a rehabilitation facility to regainenough mobility to live independently.

Removal of vertebral bone, as occurs in laminectomy and facetectomy,often leaves the affected area of the spine very unstable, leading to aneed for an additional highly invasive fusion procedure that puts extrademands on the patient's vertebrae and limits the patient's ability tomove. Unfortunately, a surgical spine fusion results in a loss ofability to move the fused section of the back, diminishing the patient'srange of motion and causing stress on the discs and facet joints ofadjacent vertebral segments. Such stress on adjacent vertebrae oftenleads to further dysfunction of the spine, back pain, lower leg weaknessor pain, and/or other symptoms. Furthermore, using current surgicaltechniques, gaining sufficient access to the spine to perform alaminectomy, facetectomy and spinal fusion requires dissecting through awide incision on the back and typically causes extensive muscle damage,leading to significant post-operative pain and lengthy rehabilitation.Thus, while laminectomy, facetectomy, and spinal fusion frequentlyimprove symptoms of neural and neurovascular impingement in the shortterm, these procedures are highly invasive, diminish spinal function,drastically disrupt normal anatomy, and increase long-term morbidityabove levels seen in untreated patients.

Therefore, it would be desirable to have less invasive methods anddevices for modifying target tissue in a spine to help ameliorate ortreat spinal stenosis, while inhibiting unwanted damage to non-targettissues. Ideally, such techniques and devices would reduce neural and/orneurovascular impingement without removing significant amounts ofvertebral bone, joint, or other spinal support structures, therebyavoiding the need for spinal fusion and, ideally, reducing the long-termmorbidity resulting from currently available surgical treatments.Furthermore, such techniques may also remove both ligament and boneduring spinal stenosis decompression. Such techniques couldsubstantially cut ligament rather than substantially tearing, ripping,or shredding it, and remove ligament without leaving a substantialamount of target ligament present after the procedure. It may also beadvantageous to have minimally invasive or less invasive tissuemodification devices capable of treating target tissues in parts of thebody other than the spine. At least some of these objectives will be metby the present invention.

SUMMARY OF THE INVENTION

Described herein are improved devices for modifying tissue and methodsof using them. These devices may be included as part of a system formodifying tissue. In general, these devices include a plurality ofblades positioned on (or formed from) rungs that are flexibly connected.The rungs may be rigid, somewhat flat and wider than they are long(e.g., rectangular), or they may have other shapes. The rungs may bearranged, ladder like, to a flexible substrate, or to one or morecable(s). Different sized rungs may be used. The blades (on the rungs)may be arranged toward the side edges of the rungs and/or in a staggeredarrangement. Any of the devices described herein may be used as part ofa tissue decompression (e.g., spinal decompression) method to modifytissue such as soft tissue (e.g., ligamentum flavum, etc.) and hardtissue (e.g., bone). In particular, these devices may be used as part ofa spinal decompression technique within a spinal foramen.

In some variations, a tissue-collection or tissue capture element (e.g.,chamber, bag, or the like) may be used to collect the cut or modifiedtissue.

As mentioned, different shaped, or differently configured rungs may beused. For example, a single device may include two or more differentkinds of cutting rungs (e.g., runs including cutting elements). In somevariations, the devices may include two or more regions, in which eachregion has a different type of rung. For example, a rungs adapted forside cutting may be located proximally or distally to rungs adapted forcutting bone, or for cutting material perpendicular to the face of thedevice.

In any of the variations described herein, the devices may include oneor more spacers between individual rungs. The spacers may be rigid orflexible, and may be shaped. Shaping the spacers my help determineprofile of the cutting surface, and may allow for tissuecollection/capture between the rungs. Variations of spacers aredescribed herein. A spacer may be attached to the same substrate (e.g.,cable, mesh, etc.) to which the cutting rungs are attached.

The devices described herein may be used as part of a guide-based accessand decompression system, including those previously described in any ofthe following patent applications and provisional patent applications,each of which is herein incorporated by reference in its entirety: U.S.patent application Ser. No. 11/250,332, titled “DEVICES AND METHODS FORSELECTIVE SURGICAL REMOVAL OF TISSUE” (filed Oct. 15, 2005), U.S. patentapplication Ser. No. 11/251,199, titled “DEVICES AND METHODS FOR TISSUEACCESS” (Oct. 15, 2005), U.S. patent application Ser. No. 11/375,265,titled “METHODS AND APPARATUS FOR TISSUE MODIFICATION” (filed Mar. 13,2006), U.S. patent application Ser. No. 11/405,848, titled “MECHANICALTISSUE MODIFICATION DEVICES AND METHODS” (filed Apr. 17, 2006), U.S.patent application Ser. No. 11/429,377, titled “FLEXIBLE TISSUE RASP”(filed May 4, 2006), U.S. patent application Ser. No. 11/538,345, titled“ARTICULATING TISSUE CUTTING DEVICE” (filed Oct. 3, 2006), U.S. patentapplication Ser. No. 11/687,548, titled “TISSUE REMOVAL WITH AT LEASTPARTIALLY FLEXIBLE DEVICES” (filed Mar. 16, 2007), U.S. patentapplication Ser. No. 11/687,558, titled “FLEXIBLE TISSUE REMOVAL DEVICESAND METHODS” (filed Mar. 16, 2007), U.S. patent application Ser. No.11/870,370, titled “PERCUTANEOUS SPINAL STENOSIS TREATMENT” (filed Oct.10, 2007), and U.S. patent application Ser. No. 12/127,535, titled“GUIDEWIRE EXCHANGE SYSTEMS TO TREAT SPINAL STENOSIS” (filed May 27,2008).

In particular, the devices described herein may use a guidewire-basedsystem that is configured so that the device may be pulled into positionand/or tensioned so as to be urged against a tissue, and thereby modifythe tissue. This configuration may be referred to as a bimanual system,since both ends (e.g., the proximal end and the distal end of thedevice) may be tensioned or pulled to modify the tissue. Tissue may bemodified by removal or smoothing of the tissue, and may be performed bypulling the devices described herein through the tissue so that theworking surface (e.g., the blades on the rungs) contacts one or moretissue surfaces.

For example, described herein are flexible tissue-modification devicesfor removing tissue from a patient. These devices may have a flexibleelongate body with an axial length, a width and a thickness, wherein theaxial length is greater than the width and the width is greater than thethickness. These devices may also include: a connector extendinglongitudinally along the axial length of the device; a plurality oftissue-cutting rungs that are flexibly connected by the connector,wherein each rung extends at least partially across the width of thebody; at least one cutting edge on each of the tissue-cutting rungs; anda plurality of spacers wherein each rung is separated from an adjacentrung by one or more spacers along the connector.

Another variation of a flexible tissue-modification device for removingtissue from a patient includes: a proximal handle; a connectorcomprising at least two flexible elongate cables, wherein the cablesextend substantially adjacent to each other from the proximal end regionof the device to the distal end region of the device; a plurality oftissue-cutting rungs extending between the cables; a plurality ofspacers wherein one or more spaces separates the tissue-cutting rungs;and at least one cutting edge on the tissue-cutting rungs, wherein theat least one cutting edge is sized and configured to cut soft tissue.

These plurality of tissue-cutting rungs may include rungs of havingdifferent configurations and/or sizes. For example, the blades may beplaced in different locations or have different shapes. The rungs mayalso be different shapes or sizes. In some variations the differentrungs may be grouped together (to for a first region, a second region,etc.). Different rungs may interact with the tissue differently, leadingto different ways of cutting and handling tissue of various types (e.g.,soft tissue, bone, etc.).

Any appropriate connector may be used. For example, the connector may bea at least one cable, a mesh or woven material, a hinged joint, or thelike. The tissue-cutting rungs and spacers may be threaded on theconnector.

Any of these tissue modification devices may also include a guidewirecoupler at the distal end of the device. In some variations, the devicesinclude a protective side guard extending along the length of theflexible elongate body.

In any of the variations described herein, the cutting edge may projectfrom the surface of the rung. Any appropriate cutting edge, as describedbelow, may be used.

The devices may also include a tissue collection region in communicationwith the rung. In some variations, the tissue modification devicesinclude at least one electrode configured for neural detection.

Any appropriate spacer may be used. For example, the spacer may beconfigured to provide a passage between adjacent rungs. In somevariations, the spacer is a ferrule.

Also described herein are flexible tissue-modification device forremoving tissue from a patient comprising: a flexible elongate bodyhaving a length, a width and a thickness, wherein the length is greaterthan the width and the width is greater than the thickness; an anteriorsurface extending proximally and distally across the width of theflexible elongate body; a plurality of cutting edges communicating withthe anterior surface; wherein the flexible tissue-modification device isconvertible from a first configuration, in which the anterior surfacehas a first proximal to distal shape, and a second configuration inwhich the anterior surface has a second proximal to distal shape; and alock for locking the proximal to distal shape of the anterior surface ofthe tissue-modification device.

In some variations, a flexible tissue-modification device for removingtissue from a patient, the device includes: a flexible elongate bodyhaving a length, a width and a thickness, wherein the length is greaterthan the width and the width is greater than the thickness; a pluralityof rungs that are flexibly connected, wherein each rung extends acrossthe width of the body and forms an anterior surface; at least onecutting edge on two or more of the rungs; wherein the flexibletissue-modification device is convertible from a first configuration, inwhich the anterior surface has a first proximal to distal shape, and asecond configuration, in which the anterior surface has a secondproximal to distal shape; and a lock for locking the proximal to distalshape of the anterior surface of the tissue-modification device.

As mentioned, any of these devices may include a connector, such as acable extending proximally and distally in the device and configured tochange the shape of the proximal to distal shape of the anterior surfaceby applying tension to the cable.

The first proximal to distal shape of the anterior surface may belinear. The second proximal to distal shape of the anterior surface maybe curved. For example, the second proximal to distal shape may be aC-shape, an S-shape, etc.

In addition, any of the devices described herein may include a guidewirecoupler at the distal end of the flexible elongate body. Any of thesedevices may also include a handle or handle attachment region incommunication with the proximal end of the flexible elongate body.

As mentioned, the anterior surface of the device may include a pluralityof flexibly connected rungs, wherein each rung extends across the widthof the flexible elongate body. The device may also include a tissuecollection region, such as a pouch, a bag, or the like. The tissuecollection region may be expandable.

Also described herein are flexible tissue-modification device forremoving tissue from a patient, the device having a flexible elongatebody with an axial length, a width and a thickness, wherein the axiallength is greater than the width and the width is greater than thethickness, the device comprising: a proximal handle; a connectorextending longitudinally along the axial length of the device; a firstset of tissue-cutting rungs that are flexibly connected to theconnector, wherein the first set of tissue-cutting rungs include atleast one cutting edge positioned between the lateral edges of eachrung; a second set of tissue-cutting rungs that are flexibly connectedto the connector, wherein the second set of tissue-cutting rungs includeat least one cutting edge positioned at a lateral edge of the rung; anda guidewire coupler at the distal end.

One aspect of the devices described herein includes a flexibletissue-modification device for removing tissue from a patient. In someembodiments, the device includes a flexible elongate body having anaxial length, a width and a thickness. The axial length is greater thanthe width and the width is greater than the thickness. The flexibleelongate body includes a plurality of rungs that are flexibly connectedand each rung extends at least partially across the width of the body.The device also includes at least one cutting edge on two or more of therungs. The cutting edges are sized and configured to cut soft tissue.

In some embodiments, the device for removing tissue from a patientincludes at least two flexible elongate cables that extend substantiallyadjacent to each other from the proximal end of the device to the distalend of the device. The device also includes a plurality of rungs thateach extend between the cables. The device also includes at least onecutting edge on two or more of the rungs. The cutting edges are sizedand configured to cut soft tissue.

The plurality of rungs may each have rounded edges along their lengthand may be connected such that a first rung is substantially contactingan adjacent rung along the length of the rung. The cutting edges mayproject from the surface of the rung. The cutting edge may project fromthe surface of the rung toward the outer edges of the rung and thecutting edge may be sized and configured to cut a strip of soft tissueand/or to cut an outline of the strip in the soft tissue. The cuttingedge may include a serrated edge, a hooked shape, a concave curvature, arounded convex curvature (e.g. a tombstone shaped edge). The cuttingedge may be hatchet shaped or hook shaped. The cutting edge may be sizedand configured to engage with soft tissue (e.g. ligamentum flavum) Therung may further include an axle about which the cutting edge mayrotate.

In some embodiments, the device further includes at least one tensioningcleat on two or more of the rungs. The tensioning cleat may be sized andconfigured to tension soft tissue (e.g. ligamentum flavum). In someembodiments, the device further includes at least one raised platform ontwo or more of the rungs. The raised platform may include a firstcutting edge and a second cutting edge. The first cutting edge may besized and configured to cut soft tissue, and the second cutting edge maybe sized and configured to engage with soft tissue (e.g. ligamentumflavum).

In some embodiments, two or more rungs include a base portion and atleast two leg portions that define a U-shaped cross section. The legportions may be flexible and/or have different lengths. The rung maydefine an opening sized and configured to receive a cable. The openingmay be larger than the diameter than the cable. In some embodiments, twoor more rungs have a cambered shape. The rung may be sized andconfigured to engage with a soft tissue such that the soft tissuebunches in the concave portion of the rung and the cutting edge mayproject from the surface of the concave portion of the rung. A hookshaped cutting edge may project from the surface of the concave portionof the rung, toward the center of the rung.

The rung may be sized and configured to engage with a soft tissue suchthat the soft tissue is over the convex portion of the rung and thecutting edge may project from the surface of the convex portion of therung. A hooked shaped cutting edge may project from the surface of theconvex portion of the rung, toward the center of the rung.

Another aspect of the devices described herein includes a flexibletissue-modification device for removing tissue from a patient. In someembodiments, the device includes at least two flexible elongate cables.The cables may extend substantially adjacent to each other from theproximal end of the device to the distal end of the device. The devicefurther includes at least one cutting edge on at least one flexibleelongate cable. In some embodiments, the cutting edge is crimped ontothe cable. In some embodiments, the device further includes a pluralityof rungs and each rung extends between the cables. The device mayfurther include at least one cutting edge on two or more of the rungs.In some embodiments, the device further includes a second set of atleast two flexible elongate cables. The second set of cables extendsubstantially in line with the first set of cables, and each rungextends between the second set of cables.

Another aspect of the devices described herein includes a flexibletissue-modification device for removing tissue from a patient. In someembodiments, the device includes a flexible elongate body having anaxial length, a width and a thickness. The axial length is greater thanthe width and the width is greater than the thickness. The deviceincludes a flexible elongate center cable that extends from the proximalend of the device to the distal end of the device and the elongate bodyincludes a plurality of rungs coupled to the cable. The cable is coupledto each rung toward the center of each rung, and each rung extends atleast partially across the width of the body. The device also includesat least one cutting edge on two or more of the rungs.

In some embodiments, the device also includes a second set of at leasttwo flexible elongate cables, coupled to each rung at substantially theedge of each rung. The rungs may be sized and configured to rotate aboutthe center cable such that the rungs maintain a substantially constantpressure against tissue across the surface of the rung. The rungs may besized and configured to rotate about the center cable such that therungs maintain a substantially constant contact with tissue across thesurface of the rung.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a vertebra with the cauda equina shown in crosssection and two nerve roots branching from the cauda equina to exit thecentral spinal canal and extend through intervertebral foramina oneither side of the vertebra.

FIG. 2A is a partially exploded, perspective view of a flexible tissuemodification device including a plurality of flexibly connected rungs.

FIG. 2B is a perspective view of another variation of a tissuemodification device with progressively larger and smaller bladesarranged along the length.

FIG. 2C is another variation of a tissue modification device.

FIG. 2D is another variation of a tissue modification device includingtwo ramp regions.

FIG. 3A shows one variation of a distal end of a tissue modificationdevice, including a guidewire coupler.

FIG. 3B shows another variation of the distal end of a tissuemodification device, including a guidewire coupler.

FIG. 4 shows a partial perspective view of a region of a tissuemodification device.

FIG. 5A is a partial perspective view of another region of a tissuemodification device.

FIG. 5B is a partial perspective view of another variation of a tissuemodification device.

FIG. 6 shows one variation of flexibly connected rungs of a tissuemodification device.

FIG. 7 shows another variation of flexibly connected rungs of a tissuemodification device.

FIG. 8A shows another variation of flexibly connected rungs of a tissuemodification device, and FIG. 8B illustrates the bending of the flexiblyconnected rungs illustrated in FIG. 8A.

FIG. 9A shows a flexible material that may be used as a connector toconnect rungs forming a tissue modification device.

FIG. 9B illustrate one variation of a rung that may be used with theconnector shown in FIG. 9A. FIG. 9C illustrates the attachment of therung of FIG. 9B onto the material of FIG. 9A, and FIG. 9D shows the rungassembled on the connector material.

FIG. 9E shows an alternative attachment of the rung of FIG. 9B onto amaterial such as the connector material of FIG. 9A, and FIG. 9F shows abottom view of the rung and connector assembly of FIG. 9E.

FIG. 9G is a partial perspective view of one variation of a tissuemodification device.

FIG. 9H is a side cross-section through the tissue modification deviceof FIG. 9G.

FIG. 10 is a bottom view of a tissue modification device includingprotective side covers.

FIG. 11 is a top view of a tissue modification device includingprotective side covers.

FIG. 12A is a side view of one variation of a tissue modification deviceincluding a fixed minimum open volume tissue collection region.

FIG. 12B is a cross-sectional view through the tissue modificationdevice of FIG. 12A.

FIG. 12C is a top view of the tissue modification device of FIG. 12A.

FIG. 12D shows a partial perspective view of a portion of a tissuemodification device.

FIG. 12E is a top view of the tissue collection region of FIG. 12D.

FIGS. 12F and 12G illustrate sections through the device shown in FIG.12D.

FIG. 13A shows one variation of a substrate of a tissue collectionregion such as the one shown in FIG. 12A-12C.

FIGS. 13B1-13B3 illustrate one variation of a substrate for a tissuecollection region in which the substrate may accordion.

FIG. 14A shows another variation of a substrate for a tissue collectionregion having expandable regions and semi-rigid regions, and FIG. 14B isa top view of a semi-rigid frame for a tissue collection region such asthe one in FIG. 14A.

FIG. 15A is a cross-section through another tissue modification devicehaving a fixed minimum open volume tissue collection region.

FIG. 15B shows a partial side view of a tissue modification devicehaving a fixed minimum open volume tissue collection region.

FIG. 15C is a cross-section through another tissue modification devicehaving a fixed minimum open volume tissue collection region.

FIG. 16A shows perspective views of two adjacent rungs havingalternating tissue cutting edges or blades, and FIG. 16B shows a sideview of both of the two rungs illustrated in FIG. 16A.

FIG. 16C shows a side view of the two rungs shown in FIGS. 16A and 16Bwhen the two rung has been positioned adjacent to each other.

FIG. 17A shows one variation of a tissue modification device having anon-linear axial shape.

FIGS. 17B-17C illustrate one variation of a tissue modification devicethat may be expanded from a first, narrower, configuration (shown inFIG. 17B), into a second, wider, configuration (shown in FIG. 17C).

FIGS. 17D-17E illustrate another variation of a tissue modificationdevice that may be expanded from a first, narrower, configuration (shownin FIG. 17D), into a second, wider, configuration (shown in FIG. 17E).

FIG. 18 is a partial perspective view of a flexible tissue modificationdevice having a non-linear axial shape.

FIG. 19A is a posterior view of the spine indicating decompression pathsat disk level and along the nerve root.

FIG. 19B is a posterior view of the spine indicating a decompressionpath for adjacent level lateral recess decompression.

FIG. 19C is a posterior view of the spine indicating a decompressionpath for central canal decompression.

FIGS. 20A-21 illustrate a variation of a rung of the tissue modificationdevice having a curved shape.

FIGS. 22A-22B illustrate a variation of a rung of the tissuemodification device having a U-shaped cross section.

FIGS. 23A-23B illustrate another variation of a rung of the tissuemodification device having a U-shaped cross section.

FIGS. 24A-F illustrate a variation of the tissue modification device.

FIG. 25 illustrates a variation of rungs having angles cutting edges.

FIGS. 26-32 illustrate variations of cutting edges of a tissuemodification device.

FIGS. 33-34 illustrate variations of cutting edges and tensioning cleatsof a tissue modification device.

FIG. 35 illustrates a rung of a tissue modification device having araised platform.

FIG. 36 illustrates a variation of a cutting edge.

FIGS. 37-38 illustrate variations of a tissue modification device havinga cutting cable.

FIGS. 39-40 illustrate variations of a tissue modification device havinga center cable.

FIGS. 41-42 illustrate variations of a rung of a tissue modificationdevice.

FIG. 43A-F illustrate one variation of a system including tools fortreating spinal stenosis. This system includes two variations of aguidewire positioning probe tool (43A and 43B), a flexible neurallocalization tool (43C), a tissue modification device (43D), a removableguidewire handle (43E), and a guidewire (43F).

FIGS. 44A-E illustrates one variation of a tissue modification devicebeing inserted into the tissue and manipulated to modify the tissue.Tools such as those shown in FIG. 43A-43F may be used for thisprocedure.

DETAILED DESCRIPTION INVENTION

Various embodiments of tissue modification devices and systems, as wellas methods for making and using tissue modification devices and systems,are provided herein. In general, a flexible tissue-modification deviceas described herein is configured to remove tissue from a patient. Inparticular, these tissue-modification devices may be configured todecompress spinal stenosis. These devices typically include a flexibleelongate body that extends proximally to distally (proximal/distal), andis configured to be inserted into a patient so that it extends aroundthe target tissue, so that it can be bimanually pulled against thetarget tissue by applying tension to either end of the device. Thus, thedevice may be extended into, through, and/or around a spinal foramen.The device is flexible in at least one plane. For example, in variationsin which the device has an elongated ribbon shape that is long and flatwith a width greater than the thickness, the device includes a firstmajor surface (e.g., a front) and a second major surface (a back), andhas edges (minor surfaces) between the first and second major surfaces.The first major surface may be referred to as the anterior or frontsurface and the second major surface may be referred to as the posterioror back surface. The devices described herein may be flexible along theanterior and posterior surfaces, and the anterior or front surface mayinclude one or more cutting edges configured to cut tissue as theanterior surface of the device is urged against a tissue. The posteriorsurface may be configured to shield or protect non-target tissue.

The tissue modification devices described herein also typically includeone or more of the following features: all or a portion of the devicemaybe formed of flexibly connected rungs or links; the devices mayinclude a tissue capture region having a fixed minimum volume; and thedevice may be configured so that the major/minor surfaces may havenon-linear shapes along their length, or may be stitched between linearand non-linear shapes. A tissue modification device may include one ormore of these features in any combination. Each of these features isdescribed and illustrated in greater detail below.

Although much of the following description and accompanying figuresgenerally focuses on surgical procedures in spine, in alternativeembodiments, devices, systems and methods of the present invention maybe used in any of a number of other anatomical locations in a patient'sbody. For example, in some embodiments, the flexible tissue modificationdevices of the present invention may be used in minimally invasiveprocedures in the shoulder, elbow, wrist, hand, hip, knee, foot, ankle,other joints, or other anatomical locations in the body. Similarly,although some embodiments may be used to remove or otherwise modifyligamentum flavum and/or bone in a spine to treat spinal stenosis,alternative embodiments, other tissues may be modified to treat any of anumber of other conditions. For example, in various embodiments, treatedtissues may include but are not limited to ligament, tendon, bone,tumor, cyst, cartilage, scar, osteophyte, inflammatory tissue and thelike. Non-target tissues may include neural tissue and/or neurovasculartissue in some embodiments or any of a number of other tissues and/orstructures in other embodiments. In one alternative embodiment, forexample, a flexible tissue modification device may be used to incise atransverse carpal ligament in a wrist while inhibiting damage to themedian nerve, to perform a minimally invasive carpal tunnel releaseprocedure. Thus, various embodiments described herein may be used tomodify any of a number of different tissues, in any of a number ofanatomical locations in the body, to treat any of a number of differentconditions.

Flexibly Connected Rungs

In some variations, a tissue modification device is formed from aplurality of flexibly connected rungs. As used herein, a rung may alsobe referred to as a link or crosspiece. A rung may be stiff (e.g., madeof a relatively rigid material) or flexible. The rungs may be connectedto or may form the anterior (front) major surface. At least some ofthese rungs include one or more cutting edges, which may be configuredas blades. The cutting edges may be formed as part of the rung, orattached to the rung.

Individual rungs may have any appropriate shape. For example, a rung mayhave a rectangular shape, an oval shape, a trapezoidal shape, or thelike. In general, the rung is relatively flat (e.g., having a thicknessthat is substantially less than the length and width). A rung may besmooth, rough or some combination. Different rungs in the same devicemay be different shapes and sizes, as illustrated below. A rung may bedirectly or indirectly connected to adjacent rungs.

Some of the rungs may be curved. For example, as shown in FIGS. 20A-20B,rung 2001 has a cambered shape. In some embodiments, the cambered rungmay be sized and configured to cut a swath of tissue 2002, for example,that may be wider than a swath of tissue cut by a non-curved rung. Morespecifically, the cambered rung may be sized and configured to cut aswath of ligament or other flexible and/or soft tissues. For example,the flexible and/or soft tissue may be ligamentum flavum in a spine of apatient. In some embodiments, the cambered rung may be sized andconfigured such that, as shown in FIG. 20A, a concave portion 2003 ofthe rung contacts the tissue such that the tissue may bunch or collectwithin the space defined by the concave portion of the cambered rung.Due to the bunching of the tissue, cutting edges 2004 (as describedbelow) coupled to the rung (particularly, cutting edges toward the sideedges of the rung) may contact the tissue at points further apart thanblades on anon-curved rung may contact the tissue, thereby cutting awider swath of tissue. In some embodiments, the cambered rung may besized and configured such that, as shown in FIG. 20B, a convex portion2005 of the rung contacts the tissue such that the tissue may be pushedapart by or stretched over the convex portion of the cambered rung. Dueto the stretching of the tissue, cutting edges 2006 (as described below)coupled to the rung (particularly, cutting edges toward the side edgesof the rung) may contact the tissue at points further apart than bladeson a non-curved rung may contact the tissue, thereby cutting a widerswath of tissue. In some embodiments, as shown in FIG. 21, a camberedrung 2101 may have cutting edges 2102 coupled to the rung toward thecenter of the rung in addition to or in alternative to cutting edges2103 coupled to the rung toward the side edges of the rung. The cuttingedges may be hook-shaped as described in more detail below.

As shown in FIG. 22A, the rung may have a “U” shape (e.g. a rounded or asquared off U-shape). The rung may include two leg portions 2201 and abase portion 2202. The leg portions may be perpendicular to the baseportion, or may be configured in any other suitable fashion. The legportions may be substantially straight, or may have a curvedconfiguration The rung may define an opening 2204 through which a cable2205 or other connector may be threaded. In some embodiments, the rungmay include a cutting edge 2203. The cutting edge may be coupled to theleg portions of the rung above the opening 2204. As shown in FIG. 22B,the U-shaped rungs may function to allow the legs of the rungs to passthrough soft tissue 2208, such as ligament, as the cutting edges cutthrough the tissue, such that the base portion of the rung does notcatch on the tissue or otherwise obstruct the cutting of the tissue. Asshown, a number of U-shaped rungs may be coupled to a cable to form amodification device. In some embodiments, spacers 2206 may be coupled tothe cable between two adjacent U-shaped rungs. The spacers 2206 mayinclude a cutting edge 2207. In some embodiments, the leg portions maybe flexible. As shown in FIGS. 23A-B, the leg portion 2301 of theU-shaped rung may be made from an expandable or stretchable material,such that as the cutting edge 2302 cuts through a tissue, the cuttingedges and leg portions may extend further into the tissue (FIG. 23B),while the base portion 2302 remains on the surface of the tissue anddoes not catch on the tissue or otherwise obstruct the cutting of thetissue.

Rungs are flexibly connected to adjacent rungs and/or to another portionof the tissue modification device. A connector, such as a cable, wire,chain, string, sheet, ribbon, mesh, fabric, or the like, may be used toconnect adjacent rungs. The connector may be flexible, or stiff. Aconnector may extend only between adjacent rungs, or it may extend alongall or a portion of the length of the device so that multiple rungs maybe attached to the same connector. More than one connector may be usedto connect adjacent rungs. For example, as shown in FIGS. 24A-F, mugsmay be connected between two parallel wires. As shown in FIGS. 24B-C,the rungs may be coupled to two parallel wires such that each rung istouching, or close to touching an adjacent rung, such that there aresubstantially no gaps between adjacent rungs. In some embodiments, theedges of the rungs are rounded such that, as the device flexes andbends, the adjacent rungs can fold or bend against one another and/orarticulate relative to one another. The rungs spaced in this manner(i.e. such that the spacing between the rungs is reduced, and/or thereare no gaps between the rungs), may function to reduce the risk of theedges of the rungs from tearing the soft tissue. The rungs spaced inthis manner may allow the rungs to move over the soft tissue withouttearing it, and may allow the cutting edges, coupled to the rungs, tocut the soft tissue. In some variations, the rungs are directlyconnected to adjacent rungs by a hinge joint or the like. Combinationsof connectors and direct connections between rungs may be used. In somevariations, rungs may be separated from each other by a space. The spacemay be an opening. In some variations, one or more spacers are used toseparate adjacent rungs. The spacing between adjacent rungs may bedifferent. In variations including one or more tissue collectionregions, the spaces between rungs may provide a passage (or via) betweenthe cutting surface on the anterior-facing surface of the rung, on whicha cutting edge may be located (or may extend from) and the tissuecollection region.

For example, FIG. 2A illustrates one variation of a tissue modificationdevice having a plurality of rungs. FIG. 2A is a partially exploded,perspective view illustrating enlargements of various regions. Thetissue-modification device shown in FIG. 2A is flexible and includesindividual rungs that may articulate relative to each other. This deviceincludes two parallel cables 201, 201′ and a plurality of rungs 205,205′, 206, 203 extend between the cables. The cables are the connectorsthat link adjacent rungs. In this example, the two cables are joined atthe proximal 233 and distal 235 regions. In some variations, the cableis joined at the proximal and distal ends, or is formed from a singlecable; in some variations the two cables are separate. At least aportion of the cable is flexible. Any appropriate cable may be used,including metal or polymeric cables. Cables may be single-filament orformed of multiple filaments. The portion of the cable towards thedistal end of the device, as shown in this example, may be hinged, andthe links between distal and proximal sections may be connected inflexible junctions. As mentioned, FIG. 24A illustrates another variationof a tissue modification device having a plurality of rungs. Thetissue-modification device shown in FIG. 24A is flexible and includesindividual rungs that may articulate relative to each other. This deviceincludes two parallel cables and a plurality of rungs 2401, 2402, 2403,2404, 2405, 2406, 2407, for example, that extend between the cables.

In some embodiments, the links or rungs 205, 205′, 206, 203 spanning thecables have different shapes and sizes. The rungs 203 in the centralregion each include one or more cutting edges 211 projecting from theanterior (target tissue facing) surface. These cutting rungs 203 mayform a tissue modifying region of the device. The cutting edges shownare triangular or pointed, although any appropriate shape may be used.Further, these cutting edges may be oriented in any desired manner; theorientation of the cutting edges may help steer or guide the device asit is urged against a target tissue to cut the tissue. In this examplethe cutting edges are oriented in parallel with the long axis (thedistal/proximal axis) of the device.

In some embodiments, the cutting edged may be angled inward toward thelongitudinal center of the modification device. In some embodiments,each rung may have cutting edges with the same orientation, or each rungmay have a different orientation or an alternating orientation. Forexample, as shown in FIG. 25, an adjacent pair of rungs may have cuttingedges that are angled in opposite directions, such that the cuttingedges are oriented or angled toward a center point. In some embodiments,the angled cutting edges may be sized and configured to guide or collecttissue toward the center point. More specifically, in some embodiments,the angled cutting edges may be sized and configured to guide or collectligament or other flexible and/or soft tissues. For example, in someembodiments, the flexible and/or soft tissue may be ligamentum flavum ina spine of a patient.

The cutting edges may have one of several suitable shapes and sizes, orany combination of shapes and sizes. In some embodiments, the cuttingedges and/or the rungs of the tissue modification device are configuredto cut soft tissue, such as ligament. The cutting edges may function tocut the ligament rather than to tear and/or shred it. The cutting edgesmay have serrated edges (FIG. 26), skate edges (FIG. 27), “shark-tooth”shaped edges (FIG. 28), “tombstone” shaped edges (FIG. 29), hatchetshaped edges (FIG. 30), roller edges (FIG. 31), and/or any othersuitable cutting edge configuration or shape. As shown in FIG. 26, insome embodiments, a serrated edge includes several smaller edges arounda portion of the cutting edge. As shown in FIG. 32, for example, in someembodiments, the cutting edge may include serrated portions along thesides 3201 of the cutting edge, while the top portion 3202 may not haveserrated edges. In FIG. 32, the cutting edge may have a flat topportion, rather than a pointed top portion. As shown in FIG. 27, in someembodiments, a skate edge includes a curved portion of the bladeoriented toward the cutting edge of the blade. As shown in FIG. 28, a“shark-tooth” edge may also include a serrated edge, and may have acurved or hooked shape. A “tombstone” shaped edge may include a roundededge. In some embodiments, the heights of the “tombstone” shaped edgevary from rung to rung.

The variation shown in FIGS. 24A-F, includes both rungs having atriangular (or other suitable shaped cutting edge) and rungs havingtombstone shaped cutting edges. In some embodiments, the tombstoneshaped cutting edges are located toward the outer side or edge of therung (FIGS. 24D and 24F), while the triangular shaped cutting edges maybe located toward the center of the rung (FIG. 24E). For example, thetombstone cutting edges may be sized and configured to cut a flexibleand/or soft tissue, including ligament, such as ligamentum flavum in apatient's spine; while the triangular shaped cutting edges may be sizedand configured to cut a rigid tissue, including bone, such as the boneof a facet joint, the bone that defines a central canal, and/or the bonethat defines a neural foramen of a spine of a patient, including apedicle. The tombstone cutting edges positioned toward the outer edgesof the rung, will cut a swath or strip of soft tissue. By positioningthe cutting edge toward the outer edge of the rung, the cutting edgewill cut an outline of the swath or strip into the soft tissue. A rungmay include fixed bone cutting edges and soft tissue cutting edges thatare flexible or foldable, such that they engage with tissue and/or popup from the rung only as desired. Alternatively, the soft tissue cuttingedges may be fixed while the bone cutting edges are movable.

In some embodiments, as shown in FIG. 30, a cutting edge has a hatchetshape. The sides 3001 of the hatchet shaped cutting edge (i.e. leadingand trailing edges), may function to hook into and slice a targettissue. More specifically, the sides of the cutting edge may function tohook into and slice a soft tissue, such as a ligament, such as aligamentum flavum in a spine of a patient. A top surface 3002 of thecutting edge may apply pressure to a tissue and cut it. For example, thetop surface may apply pressure to a soft tissue against a bone to cutthe soft tissue. The top edge of the blade may also act as a lead whentraveling over the bone to avoid ratcheting of the modification device,for example to prevent a portion of the device (such as the rungs) fromcatching on tissue or otherwise. As shown in FIG. 33, a portion of therungs of the device may include hatchet shaped cutting edges 3301, whilea portion of the rungs may include tensioning cleats 3302 that functionto pull and tension a soft tissue. In some embodiments, the cleats arelow profile and may have a blunt shape such as a blunt triangular shapeor a blunt conical shape. In some embodiments, the cleats are distal tothe cutting edges, such that as the device is pulled distally across thetarget tissue, the cleats are pulled across the tissue first and mayfunction to tension the tissue. The cutting edges may then be pulledacross the tissue and cut the tensioned tissue. A modification devicemay have cutting edges on rungs toward the center of the device, and mayhave tensioning cleats on rungs toward the proximal and distal portionof the device. In this embodiment, the tissue may be tensioned as thedevice is pulled both distally and proximally. In FIG. 34, the tensioncleats are blunt on one side 3401, and have a sharp, barbed, and/orhooked configuration 3402 on the opposite side, such that the oppositeside of the cleat may function to couple to and remove tissue. Forexample, the cleat may function to tension the tissue as the device ispulled distally, and then may function to couple to and remove thetissue as the device is pulled proximally.

In some embodiments, as shown in FIG. 31, the cutting edges may beroller edges. The cutting edges may have an axle 3101 about which thecutting edge 3102 may rotate. The cutting edge may be circular, but mayalternatively have other suitable shapes such as oval or polygonal,(e.g., a star shape). In some embodiments, the axle may be coupled to arung of the device.

In the embodiments, shown in FIG. 35, the cutting edge includes a raisedplatform 3501. In some embodiments, the raised platform is coupled tothe rung 3502 toward one side of the rung such that it may angle up fromthe rung, as shown. The raised platform may include a first cutting edge3503 and a second cutting edge 3504. In some embodiments, the firstcutting edge is coupled to the top side of the raised platform, and insome embodiments, the second cutting edge is the exposed edge of theraised platform or may be coupled to the exposed edge or underside ofthe raised platform. The first cutting edge may be located toward theouter side or edge of the rung.

The first cutting edge may be sized and configured to cut a flexibleand/or soft tissue, such as ligament (e.g. ligamentum flavum in apatient's spine). In some embodiments, the second cutting edge is sizedand configured to scrape and/or remove tissue soft tissue cut by thefirst cutting edge. The first cutting edge may be oriented towards thedistal end of the tissue modification device, such that, for example, asthe device is pulled into a patient, and/or toward a target anatomy, thefirst cutting edge cuts the target tissue. In some embodiments, thesecond cutting edge is oriented towards the proximal end of the tissuemodification device, such that, for example, as the device is pulled outof a patient, and/or away from target anatomy, the second cutting edgemay contact and/or engage with the swath of tissue, and pull the swathof tissue along with the device.

As shown in FIG. 36, the cutting edges may be hook-shaped. In someembodiments, the hook-shaped cutting edges are sized and configured tocouple to and remove a swath of tissue. More specifically, thehook-shaped cutting edges may be sized and configured to couple to andremove a swath of ligament or other flexible and/or soft tissues. Forexample, the cutting edges may be configured to remove ligamentum flavumin a patient's spine. In some embodiments, the tips 3601 of thehook-shaped cutting edges are oriented towards the proximal end of thetissue modification device, such that, for example, as the device ispulled out of a patient, or away from target anatomy, the tips of thehooked-shaped cutting edges may couple to the swath of tissue, and pullthe swath of tissue along with the device. In some embodiments, thehooked-shaped cutting edges may contact and/or engage with the swath oftissue by piercing the tissue and hooking onto the tissue.

A rung may include hook-shaped cutting edges toward the center of therung and blade shaped (e.g. triangular or tombstone shaped) cuttingedges toward the side or edge of the rung. In some embodiments, the sideedges function to cut a swath of tissue, and the hooked-shaped edgesfunction to contact and/or engage with and remove that swath of tissue.In some embodiments, a portion of the rungs may include hooked shapedcutting edges, while a portion of the rungs may have side edges. In someembodiments, the hooked rungs and the blade rungs alternate, while insome embodiments, a portion of the device includes hooked rungs and asecond portion of the device includes blade rungs.

In some embodiments, the device further includes a sheath that coversthe cutting edges while the device is being introduced into a patient.Once the device has been introduced, and/or once a swath of tissue, forexample, has been cut, the sheath may be removed, and the hook-shaped(or other suitable shaped) cutting edges may contact and/or engage withand remove the swath of tissue. In some embodiments, the sheath furtherfunctions to remove the cut tissue. The hook-shaped cutting edges may beflexible or foldable such that when they are pulled in a distaldirection (toward a target tissue), they do not engage with the tissue,and alternatively, when they are pulled in a proximal direction (awayfrom a target tissue), the hooks engage with the tissue, and may contactand/or engage with and remove the tissue. The hook-shaped cutting edgescontacting and/or engaged with tissue may be pulled out of a patient,pulling along the tissue. In some embodiments, once outside of thepatient, a user may remove (by suction, irrigation, manually, etc.) thetissue from the hooks. The device may then be reinserted to cut and/orcapture additional tissue.

The tissue modification device may include cutting edges directlycoupled to a cable, rather than including a rung with a cutting blade.As shown in FIG. 37, the cable 3701 may include cutting elements 3702such as beads, blades, wires, or other suitable cutting elements. Insome embodiments, the cutting elements may be crimped onto the wire orattached by other suitable methods. The cutting cables may cut tissueusing an energy such as heat or radio frequency energy. The energy mayfunction to desiccate and/or shrink the tissue, rather than cutting it.As shown in FIG. 37, a portion of the device may include cutting cables,while a portion of the device includes rungs threaded onto cables (withor without cutting edges on the rungs). The cutting cables and thecables onto which the rungs are threaded may be the same or differentcables. As shown in FIG. 38, a tissue modification device may includerungs 3801 along a portion of the device, and may further include acutting cable 3802 coupled to the rung portion of the device.

As mentioned above in reference to FIGS. 22A-B, the cutting cables maybe coupled to a U-shaped rung. The U-shaped rung may function to allowthe legs of the rungs to pass through soft tissue 2208, such asligament, as the cutting edges cut through the tissue, such that thebase portion 2202 of the rung does not catch on the tissue or otherwiseobstruct the cutting of the tissue. The U-shaped rung may furtherfunction to support the cutting cable, and prevent two parallel cablesfrom approximating toward one another. In some embodiments, spacers 2206may be coupled to the cable between two adjacent U-shaped rungs. Thespacers 2206 may include a cutting edge 2207.

The device may include a shield coupled to the cutting cables. Theshield may be coupled to the cutting cables such that while the cablesare adjacent to the target tissue, the shield protects the adjacentnon-target tissue, such as neural tissue, and/or may collect the tissuecut by the cutting cable. In some embodiments, the cutting cablesfunction to slide distally and proximally within or over a substantiallystationary shield. In some embodiments, the shield may function tocontact and/or engage with and remove a swath of tissue (for example,soft tissue such as ligament) cut by the cutting cables.

In some embodiments, the rungs may have varying widths along the lengthof the tissue modification device. For example, as shown in FIG. 24A,the rungs toward the distal end of the device (e.g. rungs 2401) may havea small width, while rungs towards the proximal end of the device (e.g.rungs 2404, 2405, and 2406) may have a larger. For example, the smallwidth may be on the order of 1 to 6 mm, while the large width may be onthe order of 6 to 8 mm. Thus, there may be an intermediate region alongthe length of the tissue modification device region having rungs 2402)over which the width of the device (approximately the width of the rungsin some variations) transitions from relatively narrow to relativelywider. In some embodiments, there may be rungs of a medium width in thecenter portion of the device. These transition rungs may include cuttingedges or may alternatively be non cutting rungs.

In one variation, as shown in FIG. 2B, the cutting edges may havedifferent heights on different rungs. For example, in FIG. 2B thecutting edges on the rungs toward the center of the device 298 may havea first height, while the cutting edges on the rungs toward the proximal299 and/or distal 299′ ends of the device may have a second height. Thefirst height may be larger than the second height, allowing the deviceto cut first a shallow cut, and then a deeper cut as the device ispulled along against tissue. The cutting edges in this configuration mayfunction to provide a smooth transition as the device is pulled alongagainst tissue and the sequentially higher cutting edges begin to engagewith the tissue. Alternatively, the second height may be larger than thefirst height. In some embodiments, as shown in FIG. 24, adjacent cuttingedges may have different heights. For example, in FIG. 24D a first setof cutting edges includes a cutting edge having a first height, acutting edge having a second height, and a third cutting edge alsohaving the first height. In FIG. 24D, the second height is taller thanthe first height. There may be any suitable number of adjacent cuttingedges having each of either the first height or the second height, andin some variations, there may be a number of cutting edges having anyother suitable height. As shown in FIG. 24F, a tissue modificationdevice may include a second set of cutting edges having a third height.For example, FIG. 24A, the third height may be taller than the secondand/or first height. In some embodiments (e.g. FIG. 24A) the first setof cutting edges may be distal to the second set of cutting edges.

In some variations, the cutting edges are formed from the materialforming the rung, and the cutting edge (e.g., blade) is machined as partof the rung. For example, a rung may have an initial thickness measuringthe height of the rung and the blade. The material at this initialthickness is machined (or otherwise removed) to form a series of bladesprojecting from the surface of the rung. Alternatively, the cuttingedges may be cut out of the surface of the rung, and bent out of thesurface of the rung such that the cutting edge or blade is substantiallyperpendicular to the rung. The cutting edge may be cut by Wire EDMmachining (Electrical Discharge Machining), or any other suitableprocess. In some embodiments, the cutting edges or blades may bemanufactured separately and connected to the rung.

In FIGS. 2A and 24A the rungs are threaded onto the cables by openingsor channels formed in the rung. For example, a tissue-modificationdevice such as the one shown in FIG. 2A and 24A may be formed bythreading the various components (e.g., rungs, spacers, etc.) onto thecable(s) connecting them. In some variations (described in greaterdetail below), a tissue collection region may be connected below therungs. In some variations the rungs may be rings, or may include spacefor tissue collection or a tissue-collection region.

In some embodiments, as shown in FIG. 2C, crimping elements 272, 272′may also be threaded onto the cables by openings or channels formed inthe crimping elements. Once in place, the elements may be crimped to thecable or fixed to the cable in any other suitable fashion, such as bywelding. The crimping elements fixed to the cable function to hold therungs and other various components in place, and may further function toavoid loading the proximal and/or distal portions and/or ends of thetissue modification device.

The cables or rungs in one or more regions along the device may becovered or protected. For example, in FIG. 2C, the proximal portions ofthe tissue modification device includes a protector region, such as asolid material or covering element over the cables. Thus, the tissuemodification device may have a solid proximal end protector region orportion 274. This solid portion may be a polymer extrusion, or any othersuitable material in any suitable configuration.

A widener or ramp region or regions may also be included as part of thetissue modification device. For example, FIG. 2D shows one variation ofa tissue modification device having ramp regions 288, 288′ at theproximal and distal portions of the tissue modification device. In someembodiments, the ramp begins towards the proximal and/or distal ends ofthe device, at a height approximately flush with the device, andincrease. For example, the height may increase to approximately theheight of any blades or cutting surfaces, or slightly higher. In someembodiments, the height of the ramp increases to a height approximatelyequal to or just below the height of the blades. The ramp may functionto provide a smooth transition as the device is pulled along againsttissue and the cutting edges begin to engage with the tissue. The rampmay extend across multiple rungs, a single rung, or may be coupled tothe cables of the device. The ramp may be a solid structure, or a ribbedstructure (as shown in FIG. 2D).

Rungs 203 with cutting edges 211 may extend over a portion of the lengthof the device. As illustrated in FIG. 2A, the device may include two ormore rungs with cutting edges or blades 203 (e.g., “cutting rungs”). Inthis example, these cutting rungs 203 are separated by a gap formed byspacing elements 209 between the rungs. These spacing elements are alsoattached to the connector 201, 201′ that flexibly connects the rungs. InFIG. 2A the spacers are threaded on the two parallel cables. The sizesof the connectors and/or spacing elements 209 may be varied to changethe spacing between the rungs, and also the longitudinal shape(curvature) of the device, as described in greater detail, below. Asshown in FIG. 24D, in some embodiments, a spacer 2408 may be integratedinto the rung 2404. The spacer may be sized and configured such that twoadjacent rungs define a space 2409 between them (cable 2410 can be seenin the space 2409 between the adjacent rungs).

Returning to FIG. 2A, in addition to the cutting rungs 203, other rungsmay also be included that do not have a cutting surface. For example,linking rungs 205, 205′ may be used. In FIG. 2A distal linking rungs 205are shown removed from the device, but may be included. These rungs mayprotect the cable, and/or the tissue, and may be different sizes. Nearerto the distal end 235 of the device shown in FIG. 2A, smaller rungs 206may be used to house the cable or cables connecting the rungs. Theserungs 206 may be shaped to allow the device to be flexible in one ormore direction (e.g., up/down relative to the major surface), whilelimiting the flexibility in other directions.

In some embodiments, the cutting rungs, non-cutting rungs, spacingelements, or any other suitable portion of the device may include atracking element. For example, a tracking element may be disposed in thedistal end of the device, such that the tip of the device may be trackedas it is inserted into a patient and/or moved within the patient.Alternatively, the device may include multiple tracking elementsdisposed along the length of the device, or multiple tracking elementsdisposed along a portion of the length of the device (for example alongthe cutting region of the device). In some embodiments, the trackingelement is a material that is detectable by an imaging system. Someexamples of suitable tracking elements include echogenic materials orsubstances (i.e. configured to form an echogenic surface) detectable byan ultrasound system, and radio-opaque materials detectable by aradiograph system, such as a fluoroscope. Alternatively, the trackingelement may be configured to be detectable by an MRI or Infrared system.In some embodiments the tracking element is preferably a coil configuredto be detected by an electromagnetic tracking or navigation system. Forexample, the devices described herein may incorporate a tracking systemsuch as the AXIEM™ Electromagnetic Tracking Technology, e.g., theStealthStation® AXIEM™ (Medtronic Navigation, Louisville, Colo. USA). Insome embodiments, the device is configured to generate anelectromagnetic field around a patient's target anatomy that can betracked to triangulate the positioning of devices having trackingelements.

The proximal end 233 of the device shown in FIG. 2A includes a handle231 which may be permanently or removeably attached to the proximal end.The distal end 235 shown in FIG. 2A includes a guidewire coupler 237that is flexibly attached to the distal end of the device. As shownFIGS. 24A and B, guidewire coupler 2411 is also flexibly attached to thedistal end of the device. In some embodiments, the guidewire coupler hasa tapered shape such that it has a first width at the distal end and hasa wider width toward the proximal end of the coupler. In someembodiments, the proximal end of the coupler has substantially the samewidth as rungs 2401. A guidewire coupler as shown in FIG. 24B, mayfunction to move (and thereby guide the trailing device) over, under, oraround a soft tissue, such as ligament, rather than cutting or rippingthrough the tissue.

A guidewire coupler is configured to attach to a guidewire (e.g., oneend of a guidewire) so that the device can be manipulated, at least inpart, by pulling on the guidewire after the guidewire has been securedto the device. For example, in some variations a guidewire may beinserted into the body from a first location outside of the body, thenpassed around the target tissue (e.g., around a spinal foramen) and outof the body from a second position. The distal end of the guidewire maythen be coupled to the flexible tissue modification device (such as theone shown in FIG. 2A) and pulled through the body until the tissuemodifying region of the device, e.g., the portion of the deviceincluding cutting rungs 203, is positioned opposite the target tissue.In some variations the guidewire used includes a tip region that isenlarged and may engage the guidewire coupler. For example, theguidewire may have a proximal end with a flange or ball. This enlargedregion may be configured to fit into an opening on the guidewire coupler242 so that the guidewire can be pulled distally from outside of thepatient. In some variations the distal end of the device may becompletely withdrawn, so that it can be grasped and manipulated. Inother variations, the distal end of the tissue-modification deviceremains coupled to the guidewire, and the guidewire may be grasped tomanipulate the distal end of the tissue-modification device. A handlemay be attached to the guidewire.

The overall tissue-modification device shown in FIG. 2A has an elongatebody formed of the plurality of substantially rigid rungs. Thisvariation has a length (an axial length, from proximal to distal) and awidth. The length of the device is longer than the width of each rung.In some embodiments, the ratio of the length of the device to the widthof each rung is greater than five. Alternatively, in some embodiments,the ratio may be greater than ten. The device is also relatively thin;in this variation the thickness is smaller than the width of each rung.In some embodiments, the ratio of the width of each rung to thethickness of each rung is greater than two. Alternatively, in someembodiments, the ratio may be greater than five. The use of two cablesfor the device shown in FIG. 2A allows the articulation of the links.

The distal end of the device 235 (including the guidewire couplerregion) is hinged, as is the connection to the proximal end 252. In somevariations the couplings at the proximal and distal regions allowrotation of the connection with respect to the tissue modificationregion such that torque (twisting motion) is not transferred to thetissue modification region. For example, FIG. 3A illustrates onevariation of the distal end of the tissue modification device in whichthe distal end includes a guidewire coupler 237 that is rotatablyconnected to the tissue modification device, more specifically to cable201, by connector 301. Alternatively, the distal end, including aguidewire coupler, may be rigidly attached to the cable, as shown inFIG. 3B. The distal ends of the cable include rungs 206 (as shown inFIG. 2A), protector portion, or links that cover the cable, and may helpprevent damage to tissue by presenting a relatively atraumatic surface.

In FIG. 2A, the flexible portion of the device formed by connected rungsor links is joined to the proximal end of the device, which may be lessflexible, and may include a handle or an attachment region for a handle.This interface between the links forming the flexible region and theproximal end is shown as joint 252. The proximal joint 252 near theproximal end 233 is a ball joint 207 to which the cables are attached.The ball joint allows the rotation of the handle and/or proximal portionof the device with respect to the tissue modification region of thedevice. Thus, the proximal handle may be rotated along the long axis ofthe tissue modification device, but will not substantially torque thetissue modification region of the device.

The variation shown in FIG. 2A may also include a proximal connectingregion 262 near the proximal end 233 of the device to which the handle231 is attached. This connecting region may be relatively stiff (orinflexible), or it may also be flexible.

As mentioned, in operation, the device is urged against the targettissue and may be moved in the proximal/distal direction to modify(e.g., cut) the target tissue. For example, both the proximal and distalends of the tissue-modification device may be pulled to urge the deviceagainst the target tissue, and may each be alternately pulled to agreater degree than the other handle to slide the device over the targettissue, allowing the cutting edges to cut and modify the target tissue.In this example, as the blade(s) cut the tissue, a moment is generatedbetween the tip of the blade and the base of the blade, on the rung,where the cable runs through the rung. Thus, in some variations, thebase of the blade rung must be sufficiently wide to resist rotatingabout the length of the cable. Furthermore, it may be advantageous toinclude fixed rigid sections.

In some embodiments, as rungs of the device are urged against the targettissue, a portion of a rung may contact the target tissue, while asecond portion of the rung may not. Furthermore, a portion of a rung maycontact the target tissue with a larger pressure than a second portionof the rung. It may be advantageous to maintain a substantially equalpressure and or substantially equal contact across the width of a rung.This may be achieved in one of several ways. For example, the rungs maybe flexible or jointed. In this embodiment, as the device is urgedagainst the target tissue, the rungs may function to conform acrosstheir width around the target tissue, and thereby maintain asubstantially equal pressure and or substantially equal contact acrossthe width of a rung.

In FIG. 39, the rungs 3901 are coupled to a single load bearing cable3902, running longitudinally along the device, coupled toward the centerof the device, such that the rungs may rotate about the center cable,and thereby maintain a substantially equal pressure and or substantiallyequal contact across the width of a rung. In this fashion, the rungs ofthe tissue modification device will be maintained substantially paralleland/or flush to the plane of soft tissue (e.g. ligamentum flavum),preventing the device from preferentially cutting on one side. In somecases, if the device cuts preferentially with one side, the device canslide under the soft tissue rather than cutting a swath or strip oftissue, thereby potentially leaving target soft tissue behind after theprocedure, which may be undesirable. As shown in FIG. 39, the rung mayinclude a channel or opening 3903 toward the center of the rung suchthat the rungs can be threaded onto a load bearing cable through theopening or channel formed in the center of the rung. The rung mayinclude more than a single load bearing cable toward the center of thewidth of the device. As shown in FIG. 40, the rung 4001 may includeopenings 4002 toward the sides of the rung in addition to the centeropening 4003. The rungs may be threaded onto additional side cables. Forexample, the side cables may include spacers 4004 between the rungs asdescribed above.

In some embodiments, as shown in FIG. 41, the rung is held at a firstheight 4101 above a first cable and a second height 4102 above a secondcable. A shown, the first height is greater than the second height, suchthat the rung is at an angle, and may thereby maintain a substantiallyequal pressure and or substantially equal contact across the width of arung. As shown in FIG. 42, the rung may include a channel or opening4201 that is larger than the diameter of the cable 4202 onto which therung is threaded. As shown, the rung may move on the cable such that itmay maintain a substantially equal pressure and or substantially equalcontact across the width of a rung.

In some embodiments, the cable(s) onto which the rungs are threadedremain lose prior to inserting the device into a patient. Once thedevice has been inserted, and the rungs are adjacent to the targettissue, the cables may be tightened such that both sides of the rungcontact the tissue and maintain a substantially equal pressure and orsubstantially equal contact across the width of a rung. In thisembodiment, the cables are tightened to different lengths. In someembodiments, as the device is urged against the target tissue, andpulled in a distal direction, a larger force may be applied to a firstcable than to a second cable. Then, as the device is urged against thetarget tissue, and pulled in a proximal direction, a larger force may beapplied to the second cable than to the first cable.

In some embodiments, the cables are stretchable. For example, a firstcable may stretch to a length longer than the second cable such thatboth sides of the rung contact the tissue and maintain a substantiallyequal pressure and or substantially equal contact across the width of arung. In some embodiments, the cables and/or rungs may be made out of anelastic or shape memory material. In this embodiment, the device may beinserted into a patient in a first configuration, and then once inportion, the device may shape change or reshape into a secondconfiguration, wherein the second configuration is one that conforms tothe target tissue, thereby maintaining a substantially equal pressureand or substantially equal contact across the width of a rung.

As mentioned, the rungs forming the device may be flexibly connected byhinges between the rungs. The connections shown in FIG. 2A are flexibleconnections, and individual rungs are not directly connected, but areinstead connected via a cable. Since the cable is flexible, the flexionpoint is concentrated between rung and mating ferrule (spacer).

FIG. 4 shows a portion of a tissue modification device similar to thatshown in FIG. 2A. In FIG. 4, the cutting rungs each include a pluralityof cutting edges. These cutting edges are again shown as oriented alongthe long axis of the device, although other orientations may be used.The cutting edges may be offset from each other along the long axis ofthe device, so a wider cutting area is formed. Alternating adjacentrungs may have different cutting edge configurations such that thecutting edges may be offset from each other along the long axis of thedevice. For example, as shown in FIG. 24E, a first rung may have cuttingedges in configuration 2412 such that the position of the blades isbiased toward a first side of the device (toward the top of FIG. 24A), asecond rung may have cutting edges in configuration 2413 such that theposition of the blades is biased toward a second side of the device(toward the bottom of FIG. 24A), a third rung may have cutting edges inconfiguration 2412 such that the position of the blades is biased towardthe first side of the device, and so on.

In addition the cutting edges may be spaced from the sides of the rungs,allowing the edges of the tissue modification device to be relativelyatraumatic. FIG. 4 also illustrates spacers between each rung or link,on either side of the device (i.e., on each of the cables). In FIG. 4,different spacers are shown, including relatively long ferrules 401, andbead-like spacers 403. The different spacers may modify the flexibilityof the device.

FIG. 5A illustrates a portion of the proximal end of the tissuemodification device shown in FIG. 2A in which the cables are attached tothe joint 207 by coils 501 that permit the cables to flex duringoperation. In some variations, these coils may be springs.

In some variations, as shown in FIG. 5B, the rungs forming the devicemay be flexibly connected by hinges between the rungs without spacers.The connections shown in FIG. 5B are flexible connections. Individualrungs are not directly connected, but are instead connected via a cable.Since the cable is flexible, the flexion point is concentrated betweeneach rung. The length of each rung may be designed such that everytransition point between each rung is a hinge point. As shown in FIG.5B, the rungs may be configured such that a pair of rungs defines anopening between them. This opening may provide a location through whichtissue may travel and/or be collected.

In some embodiments, as shown in FIGS. 6-8A, a tissue-modificationdevice may include flexibly connected rungs or links that do not requirethe connection by a proximal-distal cable illustrated in FIG. 2A. Forexample, FIGS. 6-8A show various methods of flexibly connecting rungs orlinks. In FIG. 6, two adjacent cutting rungs are joined together so thatthey may move relative to each other as the device is flexed. In thisexample the devices are hinged. FIGS. 7 and 8A illustrate alternativevariations similar to FIG. 6. In FIGS. 6-8B, the adjacent rungs or linksare directly connected to each other and can be bent or moved asillustrated by the arrows. As shown in FIG. 8B, the devices can be bent(at least partially). In FIG. 8B, the hinged region may be formed bybending two regions of the adjacent links over each other. In thesevariations, a separate connector (e.g., cable, etc.) is not necessary toallow adjacent links to flex. Alternatively, the hinged regions mayinclude a hinge pin (not shown).

FIGS. 9A-9D illustrate another alternative method of connecting adjacentrungs or links to allow flexion or provide flexibility. FIGS. 9A-9D showan embodiment in which adjacent links are connected via a woven ribbonto which the rungs are secured. A portion of flexible material is shownin FIG. 9A. Any appropriate (flexible) material, including meshes,woven, non-woven, and polymeric materials may be used. For example, theflexible material could be made from several materials, for example:stainless steel, aramid fibers, carbon fibers, glass fibers etc. Rungscan be attached to the flexible material by any appropriate method. Forexample, FIG. 9B shows a rung having downward-pointed edges configuredto either pierce the woven ribbon or to be bent around the connectormaterial, as illustrated in FIGS. 9C and 9D. The bottom side of thematerial and/or rungs can be softened by molding a polymer 904 to thematerial, as illustrated in FIG. 9H. The material may be formed into aribbon or band shape. Additional rungs (of different or similardimensions), may also be secured to the connector material forming thedevice.

FIGS. 9E and 9F show another variation in which the downward-pointededges of the rungs penetrate the material and pass through it so thatthey can be and secured to it. For example, In FIG. 9E, the downwardpointing edges pierce the material (though the material may also includepre-formed holes). The downward-pointed regions can then be bent back upto secure the rung to the connector material. Other means for fasteningthe rung to the connector material may also be used. In the exampleshown in FIGS. 9E-9G, the edge of the rungs is not concurrent with theedge of the tissue-modification device. FIG. 9G shows a portion of anexemplary tissue-modification device including a flexible connectorconnecting multiple rungs having cutting edges extending from them. InFIG. 9, the rungs are spaced from the edge of the tissue cutting device,and an atraumatic edge 903 is included along the outer periphery (alongthe major surface).

Spacing the rungs from the edge in this manner may reduce the risk ofside cutting. Other variations, including variations having a connectorcable(s), the cable and rungs can be protected on the side by a separatetube like elements on the edges that are interlaced with the rungs andthe cable, as illustrated in FIGS. 10 and 11. In FIG. 10, for example,the cables 1001, 1001′ on either sides of the device are covered by aprotective cover 1003. Rungs 1005 span the distance between the twocables. FIG. 11 shows a slightly higher magnification of the tissuemodification region of the device shown in FIG. 10. In FIG. 11, thecutting edges 1101 are shown extending from the rungs.

Fixed Tissue Capture Region

The blade rung “ladder” design described above for the tissuemodification devices having flexibly linked rungs may include spacesbetween the rungs. In some variations the tissue cutting region may alsoinclude holes or openings. These spaces between the rungs, holes, and/oropenings may form part of a tissue capture region, or may act as vias orchannels to direct cut tissue into a tissue capture region. As thetissue modification region modifies and/or removes the tissue, at leasta portion of (and preferably the majority of) the cut tissue may belodged between the cutting edges or blades and/or between the rungs ofthe device, such that the captured tissue is removed from the patientalong with the device as the device is removed from the patient.Alternatively, in some variations, the space between the rungs maychannel cut tissue into a tissue capture region. As the cutting edges(e.g., the triangular “teeth” shown in some of the figures, above) cutthe tissue, the tissue may be driven into a tissue capturing orcollection region. In some variations, the edge of the adjacent rung mayshear the tissue as the device is urged against the tissue and moved. Insome variations, the edge of the rung may also be sharp, or may includea sharp region. Thus, tissue may pass through the blade rungs and into atissue collection region. The (typically upward) pressure of urging thedevice against the target tissue may therefore aide in packing thetissue into a tissue capture region. In some embodiments, the device mayhave elements to aid in the movement of the cut tissue. For example, therungs may be designed such that two adjacent rungs function as a one wayvalve, allowing the tissue to enter through the space between the rungs,and then kept between or below the rungs and prevented from moving backout. Each rung may include a flap or a wing that couples to a flap orwing of an adjacent rung to function as a one way valve. The rungs mayalternatively be designed in any other suitable fashion.

In general, a tissue capture region may require some amount of force orpressure to drive the cut tissue into the capture region. This may beparticularly true for expandable tissue capture regions, such as anexpandable bag that is attached behind the tissue modification regionbehind or within the rungs including cutting edges). As the tissue fillsthe area below the blades, the bag may expand to accommodate theincrease volume. Increased pressure may be required to ‘pack’ the tissueinto the tissue cutting region.

In some applications it would be beneficial to provide pre-expandedtissue capture regions, or tissue capture regions having a minimumvolume that is fixed. The fixed minimum volume typically refers to afixed open volume. Fixed minimum volume tissue capture regions typicallyinclude a minimum open volume, but this open volume may be increased asthe device is operated; for example, the volume may be expandable fromthe fixed minimum open volume. Alternatively, the total volume of thetissue capture region maybe fixed or predetermined. Having a fixedminimum open volume allows tissue to enter the tissue capture regionwithout having to apply additional force to drive the tissue into thetissue capture region.

In some variations a tissue collection region having a fixed minimumopen space may be defined by the space between the openings into thetissue collection region (which may be the rungs of the tissuemodification region) and a tissue collection substrate. The tissuecollection substrate is typically spaced apart from the tissuemodification side of the rungs by a thickness that forms the open space.The tissue collection region may have a length that extends at leastalong the tissue modification region of the tissue modification device(e.g., the cutting rungs in variations including rungs), but may extendfurther proximally/distally.

For example, FIGS. 12A-12C illustrate one variation of a tissuemodification device including a tissue collection region having a fixedminimum open space. FIG. 12A shows a cross-section along the tong(distal/proximal) axis of the device. In this variation the deviceincludes a plurality of flexibly connected rungs 1205 that are connectedby a connector (a cable 1215). The rungs in the tissue modificationregion include cutting edges 1209. A tissue collection region 1219(illustrated in FIG. 12B) is formed between the top of the rungs 1205and a tissue collection substrate 1211. In this example, the tissuecollection substrate 1211 is a semi-rigid substrate element that extendsalong the proximal/distal length of the device. In some embodiments, thesubstrate element may additionally include guiding features to moveand/or position the tissue in a desired direction, such as toward theouter portions of the device, beneath the non-cutting rungs. Forexample, a guiding element may be one or more ridges in the substratethat are arrow or chevron shaped, with the vertex of the shape pointedtoward the outer regions of the device. The distal end of this variationalso includes a guidewire coupler or coupling region 1252, andindividual links 1205 may be separated by spacers (shown as ferrules)1245.

FIG. 12B shows a cross-section through one of the rung elements 1205shown in FIG. 12A. In this variation, the rung 1205 includes twochannels 1216 and 1216′ through which the cables 1215 (FIG. 12A) maypass. The top (anterior) of the rung includes a plurality of cuttingedges 1209. Within the rung 1205 is a fixed open volume 1219 that isformed between the top of the rung and a tissue collection substrate1211 on the bottom of the rung. The tissue collection substrate may besecured within the rung by loops or straps 1223 that extend across thebottom of the rung. FIG. 12C shows a top view of the tissue modificationdevice of FIGS. 12A and 12B.

The tissue-collection substrate portion of the tissue modificationdevice shown in FIGS. 12A-12C is slideable within the rungs (e.g., alongthe straps of the rungs). One end of the tissue collection substrate maybe fixed (e.g., near the distal end of the device) and the other end mayinclude an elastic or spring element 1272 that allows thetissue-collection substrate to slide as the tissue modification deviceis bent during operation. FIGS. 13A-13D illustrate variations oftissue-collection substrates that may be used. For example, in FIG. 13A,the tissue collection substrate 1211 is a semi-rigid sheet of materialas shown in FIG. 12A-12C. The tissue-collection substrate may be formedof any appropriate material, including metals or alloys (e.g., stainlesssteel, titanium, NiTi, aluminum, etc.), plastics (e.g., PEAK, PET, PP,EP, PET, etc.), and elastic materials (e.g., urethanes, silicones,etc.). Other materials may also be used. Since the overall device(including the tissue collection substrate) is flexible at least in theplane forming the major surfaces, the tissue collection substrate may bebendable. Thus, when more rigid materials are used (e.g., metals) toform the substrate, the substrate may be relatively thin.

FIGS. 12D-12G illustrate another variation of a tissue modificationdevice including a tissue collection region having a fixed minimum openspace. FIG. 12D shows a perspective view of a portion of a tissuemodification device including a tissue collection region 1262. Thistissue collection region has sides and a bottom region, and includes achannel through which connectors (shown as cables 1266, 1266′ in FIG.12D) may pass. The tissue collection region may be a single, flexiblepiece, as indicated in FIG. 12D, or it may be a plurality of pieceslinked by the connector. In this variation, the tissue collection regionalso includes spaced into which rungs may fit so that the connectors maypass through the rungs. This is also apparent from the top view shown inFIG. 12E. FIGS. 12F and 12G illustrate sectional views taken through aportion of the tissue modification device including a cutting run (shownin FIG. 12F) and a portion of the tissue modification device that isbetween adjacent cutting rungs (shown in FIG. 12G).

Alternatively, the tissue collection region may include projections thatproject into a space or slot formed on the rungs; the connectors maypass through these projections and through the rungs. In addition,spacers (e.g., ferrules, beads, etc.) may be used between the rungs.

In some variations, the substrate may be configured to expand/contractas the tissue modification device is flexed. For example, as describedabove, in some variations the tissue collection substrate may beconnected at one (or both) axial ends via a spring or elastic member.FIGS. 13B1 to 13B3 illustrate a side view of another variation of asubstrate that is configured to accordion along its length as the deviceit is attached to is flexed. For example, when the tissue modificationdevice is flexed or bent in a first direction the substrate may contractor accordion closed, as shown in FIG. 13B1. In the relaxed state thesubstrate is ‘neutral’, with folds that may be expanded or contracted,as shown in FIG. 13B2. When the tissue modification device is bent in asecond direction the substrate may expand or accordion open, as shown inFIG. 13B3.

In an alternative variation the substrate is expandable, and includesrigid edge with an expandable element between, as illustrated in FIG.14A. In this variation the rigid portion may be secured to the tissuecollection device (e.g., to the links of a tissue collection device),and the expandable portion may be made of a mesh or thin plasticmaterial. FIG. 14B shows just the rigid portion of one variation of thisembodiment, in which the rigid frame 1401 surrounding an expandableportion 1403 includes cross-struts 1407. Substrates including expandableregions may be useful to allow the tissue collection region to expandeven beyond the minimum fixed volume, allowing the collection ofadditional tissue even after the minimum fixed volume is filled.

In general, the tissue collection substrate may be held to the tissuemodification device by one or more connectors linking the tissuecollection substrate to the rung. In FIGS. 12A-12C the tissue collectionregion is bounded by the tissue collection substrate that is secured tothe link via a strap or loop that is formed by the rung. In somevariations the connectors are not part of the rungs, but are separateelements. For example, FIGS. 15A-15C illustrate variations in which thetissue collection substrate is secured to the device by a cable or rodconnector between each rung and the tissue collection substrate. In somevariations, the connector is formed as a part of the tissue collectionsubstrate. FIG. 15A shows a cross-section through a flexible tissuemodification device having rungs 1501 and a tissue collection region1509 that is formed between the top of the rung 1501 and a substrate1511 that is secured to the rung by a pair of cables 1515, 1515′ orrods. FIG. 15C shows a similar variation in which the substrate issecured to the rung by connectors that may swing or slide. As described,the rung shown may be flexibly connected via one or more cables 1503,1503′. In all of these examples of tissue collection regions there is aminimum open volume that has a fixed minimum, so that, even when flexed,the tissue collection region has a non-collapsible open space so thattissue can enter the space. In some variations this minimum fixed spaceis formed by a separation of between about 2 and about 6 mm between therung forming the top of the space and the substrate.

FIG. 15B shows a cross-section through the tissue modification region ofa tissue modification device including rung and tissue collection designshown in FIG. 15A. As before, the tissue collection substrate in thisexample is shown axially connected to the device via a spring 1511.

In operation, tissue cut by the blades may be collected into the tissuecollection regions described. As mentioned, openings between the rungsmay act as channels or vias through which cut tissue may pass into thecollection region(s). In some variations, the tissue modification devicemay include openings adjacent to the cutting edge(s) through whichtissue may pass. Although the examples described above include tissuecollection regions having a fixed minimum open volume as part of atissue modification device comprising a plurality of rungs, a fixedminimum open volume tissue collection region may be incorporated as partof any tissue collection region, even those not having rungs.

Other examples of tissue capturing mechanisms which may be used aredescribed, for example, in U.S. Ser. No. 11/687,558 (titled “FLEXIBLETISSUE REMOVAL DEVICES AND METHODS”), filed on Mar. 16, 2007, and U.S.Ser. No. 11/687,548 (titled “TISSUE REMOVAL WITH AT LEAST PARTIALLYFLEXIBLE DEVICES”), filed on Mar. 16, 2007, and U.S. Ser. No. 11/952,934(titled “TISSUE REMOVAL DEVICES AND METHODS”), filed on Dec. 7, 2007;these references are all incorporated by reference herein.

As mentioned above, the spacing and orientation of the cutting edges ofthe tissue modification devices may be arranged to optimize performance.For example, FIG. 16A to 16C illustrate one arrangement of cutting edges(blades) in which adjacent rungs have blades that are offset from eachother. Offsetting the blade in this manner may allow them to moreuniformly cut as the device is operated to modify tissue. Blade densitymay be important when it comes to cutting both soft tissue and bone. Toimprove the density and allow for material to pass through blade teeth,the leading and following blades may be interdigitated. FIGS. 16A-16Cshow the interdigitation of a set of blades. The first rung 1601(Rung-A) cuts a leading path and the second rung 1603 (Rung-B) cuts afollowing path. This arrangement of cutting edges and rungs may helpmaximize the material removal for one cut stroke. FIG. 16C is a sideview of Rung-A directly in front of Rung-B.

Non-Linear Shapes and Shape Morphing

In addition to the substantially linear tissue modification devicesdescribed above, any of these tissue-modification devices may also beconfigured to have a non-linear shape (e.g., axial shape) and/or beshape-morphing devices that can convert between linear and non-linearshapes. Non-linear devices may be pre-formed into a curved or bent shape(such as “s”-shaped, or serpentine, device or “c”-shaped devices, or thelike). Alternatively, a non-linear device may be a shape-morphing devicethat can be changed from a linear to a non-linear shape, either beforeor during use of the device to modify tissue.

The phrase ‘linear’ and ‘non-linear’ shapes typically refer to the shapeof the device along the major (distal/proximal) axis, when looking downon the major (tissue-modifying) surface.

For example, FIG. 17A illustrates a device having S-shape (orserpentine) shape. This is a non-linear device (since the major surfacedoes not travel in a line, but is curved). The device can be constructedusing the cable (or wire) rung design, as illustrated in FIG. 18. InFIG. 18, the links are separated by one or more spacers that are unequalin length from one side of the device (e.g., one cable) to the other.This difference in spacing causes the device to curve, as shown. Forexample, the side of a device with a larger radius of curvature mayinclude spacers such as relatively long ferrules 401 (shown in FIG. 4),and the side of a device with a smaller radius of curvature may includebead-like spacers 403 (shown in FIG. 4). Curved devices may have a widerstroke length when cutting the tissue, and may therefore cut a widerregion of tissue. For given stroke length, the amplitude (peak to peakof the curve) becomes the effective width of the device, producing akerf wider than the individual rung.

Additionally the devices can be deployed into the spine in a linearconfiguration and then changed to a non linear configuration. Thisconversion in shape may be achieved in-situ by pulling on a cable on oneside of the rung more than the other side. Alternatively, you can pullboth sides with the same tension in combination with variablycompressible ferrules/spacers between the rungs in selected locations.For example to achieve a concave curve to the device on the right side,the right side would have more compressible ferrules (elastomeric) thanthe left side. Once the new non-linear shape was achieved, the cablewire(s) could be locked in position near the proximal end and/or handle.If desired, the cables could be readjusted to form a linear shape to thedevice prior to device removal. For example, a device may be increasedin width by shift parallel links from an oblique angle to perpendicularwith the cable, shown in the images below.

In some variations, the shape-morphing devices may be transitionedbetween a first straight (e.g., linear) configuration and a secondstraight configuration, with the first configuration being narrower thanthe second configuration. Two examples of this are shown in FIGS.17B-17C and 17D-17E. In FIG. 17B the tissue modification device has arelatively narrow profile and can be expanded into a wider profile asillustrated in FIG. 17C. The rungs in 17B are initially diagonal,relative to the parallel cables flexibly connecting them. By pulling onone of the cables, one side of the device to which the rungs areconnected, may be pulled to align the rungs perpendicular to the longaxis of the device. Since the rungs are relatively rigid, this willexpand the width of the tissue modification device, as indicated in FIG.17C.

FIGS. 17D and 17E illustrate a similar variation, in which the tissuemodification device may be expanded from a first linear configuration,in which the rungs are chevron-shaped when viewed from the top as inFIG. 17D, to a second linear configuration that is wider, in which therungs can be pulled so that they are perpendicular to the long axis(proximal/distal axis) of the device, as illustrated in FIG. 17E. Inthis variation, a cable, pull wire, or the like may be connected to therungs to convert them from the first to the second shapes. The rungs maybe adapted hinged) for conversion. In some variations each run isactually a two rungs that are joined end-to-end.

Decompressing Spinal Regions

Any of the tissue modification devices described herein may be used todecompress one or more spinal regions, as mentioned above. Inparticular, any of these devices may be used to decompress nerve rootsplaced within the spinal anatomy along various paths, including thoseshown in FIGS. 19A-19C. Because these devices are flexible, and may beappropriately sized and shaped to fit within a neural foramen, thesedevices may be used to accesses appropriate regions of the spine from asingle access point (e.g., from the patient's midline or near-midlineregion). The procedure may be used to decompress spinal nerve roots onthe unilateral or bilateral side from the access point. A probe or guidemay be introduced into the spinal epidural space (or along or justwithin the ligamentum flavum) at an appropriate spinal level using imageguidance and/or tracking (e.g., electromagnetic tracking). In someembodiments, in which the probe or guide may be introduced just withinthe ligamentum flavum, the device may be used to cut a portion of theligamentum flavum and in some cases may be used to cut a portion of theunderlying bone, while leaving the surface of the ligamentum flavumintact. Introduction may be either via percutaneous puncture or openlaminotomy.

As shown in FIG. 19A, the device may be used to decompress anipsilateral or contralateral proximal nerve (in a lateral recess). Aguide may be deployed immediately cephalad to the caudal segment pedicleon the appropriate side (e.g., location 1810). This access point can beconfirmed radiographically. If neural structures adjacent to the guidecannot be directly visualized, the relationship of these structures tothe guide or tissue modification devices can be determined usingelectrical stimulation, ultrasound imaging, endoscopic mean or othertechniques. In some variations, once the guide is deployed and optionalneural localization is complete, a guidewire is passed via thecannulated guide. The guidewire can be sharp on its distal end andpenetrate the skin dorsolaterally after exiting the foramen. Theguidewire may include a wire exchange tip on its proximal end, asmentioned above. As shown in FIG. 19A, the guidewire may be threadedalong a path from location 1810 to where it exits through the foramen,as shown by at least one of arrows 1812 (for ipsilateral decompressionof the nerve root origin at the disk level) and 1814 (for contralateraldecompression of the nerve root origin at the disk level). In someembodiments, the probe/guide is removed once the guidewire has beenpositioned.

Next, a flexible tissue modification device is attached to the proximalwire exchange tip, and a distal handle may be secured to the distal wiretip. The device can then be introduced into the epidural space and theninto the lateral recess by careful upward force applied to the distalhandle. In some embodiments, the device is pulled by the guidewire onthe path through the spinal anatomy. As described above, suitable pathsinclude paths shown by arrows 1812 and 1814 to decompress the nerve rootorigin at disk level. Once the device is in place as confirmed visuallyor radiographically, bimanual reciprocating strokes may be utilized todecompress dorsal impinging bone or soft tissue at the nerve rootorigin. In some embodiments, approximately 30-40 reciprocating strokesare required to complete the decompression. This may be confirmedradiographically or with palpation by instruments. The device may thenbe detached and the wire removed.

The probe/guide may be reinserted to decompress the ipsilateral orcontralateral distal (foraminal) portion of the nerve root, so that thesame (or a different) tissue modification device may be used todecompress another region of the spine (or nerve root) using the sameaccess or entry site. Thus, a guide may be deployed immediately caudalto the caudal segment pedicle on the appropriate side. The guide may bedeployed in the same access point (location 1810) as described above.Transforaminal positioning and the relationship to neural elements canagain be confirmed visually, radiographically, and/or with electricalstimulation, ultrasound or alternative means. Once appropriatelocalization is confirmed, the guidewire can be passed and probe/guideremoved. As shown in FIG. 19A, the guidewire may be threaded along apath from location 1810 to where it exits through the foramen, as shownby at least one of arrows 1816 (for ipsilateral decompression along thenerve root) and 1818 (for contralateral decompression along the nerveroot). A handle is attached to the distal guidewire and the tissuemodification device to the proximal exchange tip. The device is thenintroduced into the spine (e.g., the epidural space, or the regionanterior to the posterior edge of the ligamentum flavum) with carefulupward force applied to the distal handle. In some embodiments, thedevice is pulled by the guidewire on the path through the spinalanatomy. As described above, and as shown in FIG. 19A, suitable pathsinclude paths shown by arrows 1816 and 1818 to decompress along thenerve root. The foraminal decompression is performed using bimanualreciprocating strokes to remove impinging bone and soft tissue. In someembodiments, approximately 30-40 strokes are required to decompress theroot. Confirmation of decompression may be done radiographically orusing instruments to palpate along the root. The device can then bedetached and the guidewire removed.

As shown in FIG. 19B, the devices described herein can used todecompress the ipsilateral or contralateral (not shown), or both,regions adjacent the level proximal to the nerve root (lateral recess).A guide may be deployed in the same access point (location 1810) asdescribed above. Transforaminal positioning and the relationship toneural elements are once again confirmed visually, radiographically,and/or with electrical stimulation, ultrasound or alternative means.Once appropriate localization is confirmed, the guidewire may be passedand the probe/guide removed. As shown in FIG. 19B, the guidewire canthen be threaded along a path from location 210 to where it exitsthrough the foramen, as shown by arrow 220 (for ipsilateraldecompression of the adjacent nerve root origin). A handle can beattached to the distal guidewire and the guidewire can then be attachedto the distal end of one of the tissue modification devices describedherein. The device can then be introduced into the spine by pulling onthe guidewire. In some embodiments, the decompression device is pulledby the guidewire on the path through the spinal anatomy as illustratedin FIG. 19A, 19B, or 19C. As described above, and as shown in FIG. 19B,suitable paths include the path shown by arrow 1820 the adjacent nerveroot origin. The lateral recess decompression may be performed usingbimanual reciprocating strokes to remove impinging bone and soft tissue.In some embodiments, approximately 30-40 strokes are required todecompress the nerve. Confirmation of decompression may be doneradiographically or using instruments to palpate along the root.

As shown in FIG. 19C, a probe/guide may be used to introduce a tissuemodification device as described herein to decompress the central canal.The guide may be deployed in the same access point (location 1810) asdescribed above. Once appropriate localization is confirmed, theguidewire may be passed and probe/guide removed. As shown in FIG. 5, theguidewire can be threaded along a path from location 1810 to where itexits through the intralaminar window, as shown by arrow 1822 (not theadjacent foramen). A handle may be attached to the distal guidewire and,the tissue modification device may be coupled to the proximal end of theguidewire. The device can then be introduced into the epidural space bypulling the distal end of the guidewire on the path through the spinalanatomy, drawing the device into position adjacent the target tissue inthe spinal canal. As described above, and as shown in FIG. 19C, suitablepaths include the path shown by arrow 1822 to decompress tissueassociated with the central canal and may be effective in treatingpatients with central spinal stenosis. The decompression may beperformed using bimanual reciprocating strokes to remove impinging boneand soft tissue. In some embodiments, approximately 30-40 strokes arerequired to decompress the root. Confirmation of decompression may bedone radiographically or using instruments to palpate along the nerve.

In some embodiments, the probe, guide, or guidewire may also include atracking element or plurality of tracking elements. The tracking elementmay be similar to the tracking element of the tissue modificationdevice. As described above, in some embodiments the tracking element isa material that is detectable by an imaging system, while in someembodiments the tracking element is preferably a coil configured to bedetected by an electromagnetic tracking or navigation system.

Any of the procedures described herein can be done in combination withother techniques including an open or minimally invasive decompressionprocedure where tools such as rongeurs and powered drills are used toremove tissue primarily around the proximal end of nerve root (lateralrecess). Such techniques may include laminotomies, etc.

FIGS. 43A-F illustrate one variation of a system including oneembodiments of the tissue modification device described above. Any ofthe tissue modification devices (and embodiments of these devices)described herein may be included in a system for treating spinalstenosis. In this variation, the system includes two types of tools forpositioning a guidewire (43F), as shown in 43A and 43B. These tools aretypically cannulated devices that may be used to position the guidewirearound the target tissue. These cannulated tools may be steerable, ormay have distal ends that are curved and/or extendable for steering theguidewire around the target tissue. During guidewire positioning, thelocation of one or more nerves may be configured using a neurallocalization device (e.g., FIG. 43C) that is configured to be positionedby pulling into place using the guidewire, similar to the methoddescribed herein for positioning an operating the tissue modificationdevice. The neural localization device may include one or moreelectrodes for creating a localized electromagnetic field capable ofstimulating only nearby nerves (thereby confirming they are adjacent tothe pathway of the guidewire, or one or more sides of the guidewirepathway). In some variations the tissue modification device includes oneor more neural localization devices. A handle may also be included, forattaching to the guidewire, better control of the guidewire. Forexample, in the system shown in FIGS. 43A-43F, the handle (FIG. 43E) isconfigured to connect to the guidewire (FIG. 43F), allowing the distalend of the guidewire to be pulled when the proximal end of the guidewireis coupled to the tool (e.g., the tissue modification device, FIG. 43D).

Any of the devices illustrated herein may be used to modify tissue, asdiscussed above. FIGS. 44A-44E illustrate one embodiment of a method formodifying tissue using one of the flexible tissue modification devices10 described herein. In FIGS. 44A-44E, a patient's skin, target tissueTT and non-target tissue NTT are shown diagrammatically, rather than asspecific structures. In one embodiment, the method of FIGS. 44A-44E maybe employed in the spine, to remove ligamentum flavum, bone or both,with device 10 passing through an intervertebral foramen between twovertebrae. In other embodiments, other tissue in other areas of the bodymay be removed.

As shown in FIG. 44A, guidewire 22 with sharp tip 23 and shaped end 27may be passed into the skin, between target and non-target tissue, andout of the skin. The guidewire may also be referred to a pullwire, sinceit is used to pull one or more devices into position, as described.Methods for passing guidewire/pullwire 22 are described further, forexample, in U.S. patent application Ser. Nos. 11/457,416, 11/468,247 and11/468,252, which were previously incorporated by reference. Asdescribed in those references, in various embodiments, guidewire 22 maybe placed using a percutaneous method, such as with a needle, or usingan open method, such as with a probe. In some embodiments, localizationof neural tissue, such as with nerve stimulation on a guidewire passingprobe or guidewire passing guide member may be used, to confirm thatguidewire 22 is passed between target and non-target tissue. Forexample, a neural localization device (as shown in FIG. 43C, above) maybe used by pulling into position using the guidewire/pullwire.

In some embodiments where the method is performed in the spine, one ormore substances or devices may be placed into the epidural space of thespine before or after placing guidewire 22, to create additional spacebetween target tissues, such as ligamentum flavum, and non-targettissues, such as cauda equina and nerve root. Substances may include,for example, any of a number of fluids or gels, such as radiographiccontrast medium. Devices may include, for example, a barrier or shielddevice. Injection of substances into the epidural space to create asafety zone is described in U.S. patent application Ser. No. 11/193,557(Pub. No. 2006/0036211), titled “Spinal Ligament Modification Kit,”assigned to X-Sten, Inc., and filed Jul. 29, 2005, the full disclosureof which is hereby incorporated by reference. Various barrier devicesfor placement in the spine are described, for example, in U.S. patentapplication Ser. No. 11/405,859, titled “Tissue Modification BarrierDevices and Methods,” and filed Apr. 17, 2005, the full disclosure ofwhich is hereby incorporated by reference.

Referring to FIG. 44B, distal handle 24 (another variation of which isshown in FIG. 43E) may be passed over sharp tip 23 and tightened aroundguidewire 22, such as by moving tightening lever 25. In some variations,the handle captures or otherwise holds the sharp distal tip, to preventinjury or interference. Distal handle 24 may be coupled with guidewire22 at this point in the process or at a later point, according tovarious embodiments.

As shown in FIG. 44C, guidewire 22 may next be coupled with proximaldevice portion 11, by coupling shaped guidewire end 27 (not visible)with guidewire coupler 18. In the embodiment shown, for example,guidewire shaped end 27 may be placed into coupling member 18(hollow-tipped arrow).

Referring to FIG. 44D, distal handle 24 may then be pulled(hollow-tipped arrow) to pull device 10 into the patient and to thusposition tissue modifying members 16 in contact with target tissue TT.In some embodiments, such as when device 10 is used in a spinalprocedure and passes through an intervertebral foramen, a surgeon orother physician user may use tactile feedback of device 10 passing intothe foramen, such as when coupling member 18 and/or tissue modifyingmembers 16 pass into the foramen, to determine when tissue modifyingmembers 16 are positioned in a desired location relative to targettissue TT. Alternatively or additionally, a surgeon may confirm that adesired placement has been achieved by using radiographic imaging, suchas fluoroscopy, direct visualization, such as in an open surgical case,or a combination of multiple methods.

In some embodiments in which device 10 is used in the spine to treatspinal stenosis and/or neural or neurovascular impingement, device 10may be passed into the patient and to a position for modifying tissuewithout removing any vertebral bone. More specifically, in someembodiments, device 10 may be advanced into the patient, through anintervertebral foramen, and out of the patient without removing bone.This is contrary to the majority of current surgical methods fortreating spinal stenosis, which typically include removal of at leastsome vertebral bone, such as performing a laminotomy or laminectomy, andwhich often remove significant amounts of vertebral lamina, spinousprocess, facet and/or pedicle bony tissue, simply to access the surgicalsite. In one embodiment, for example, device 10 may be advancedpercutaneously into the patient, used to remove ligamentum flavum only,and withdrawn from the patient, without removing any vertebral bone.

As shown in FIG. 44E, once tissue modifying members 16 (e.g., rungsincluding tissue modification surfaces, as described above) arepositioned as desired, relative to target tissue IT, proximal handle 20and guidewire handle 24 may be pulled (hollow-tipped arrows) to urgetissue modifying members 16 against target tissue TT (solid-tipped,single-headed arrows). While maintaining pulling/tensioning force,handles 20, 24 may be used to reciprocate device 10 back and forth(solid-tipped, double-headed arrows) to remove target tissue TT. In somevariations, the tissue modification device includes a rigid (orsemi-rigid or rigidifiable) proximal shaft portion 13 that may be usedto help steer device 10, or more specifically flexible distal shaftportion 114, relative to the target TT. For example, a rigid shaftportion 113 may be used to move flexible portion 14 laterally or topivot shaft 12 about an axis located along flexible portion 14. In oneembodiment, for example, rigid portion 13 may be used to manipulateflexible portion 14 within an intervertebral foramen, such as bypivoting shaft 12 or moving flexible portion 14 laterally in a caudaland/or cephalad direction, relative to the patient. The rigidity ofrigid proximal shaft portion 13 may generally facilitate such steering,as compared to a completely flexible device.

When a desired amount of tissue is removed, device 10 may be removedfrom the patient, such as by detaching guidewire handle 24 fromguidewire 22 and pulling proximal handle 20 to withdraw device 10 andguidewire 22 out of the patient. In some embodiments, device 10 or anadditional device may be reinserted into the patient and used in asecond location to remove additional tissue. For example, in a spinalstenosis treatment procedure, device 10 may be used to remove tissuefrom (and thus decompress) a first intervertebral foramen and then my beremoved and reinserted to remove tissue from a second foramen. Thisprocess may be repeated to remove tissue from any number of foramina. Inone embodiment, device 10 may include a guidewire lumen, so that aguidewire may be placed into a second foramen while device 10 is in theepidural space of the patient. Device 10 may then be removed along withthe first guidewire 22, attached to the second guidewire, and reinsertedinto the second foramen to remove tissue. In some embodiments, tissuemay be removed from device 10 before reinserting device 10 into thepatient to remove more tissue.

Although various illustrative embodiments are described above, any of anumber of changes may be made to various embodiments without departingfrom the scope of the invention as described by the claims. For example,the order in which various described method steps are performed mayoften be changed in alternative embodiments, and in other alternativeembodiments one or more method steps may be skipped altogether. Optionalfeatures of various device and system embodiments may be included insome embodiments and not in others. Therefore, the foregoing descriptionis provided primarily for exemplary purposes and should not beinterpreted to limit the scope of the invention as it is set forth inthe claims.

What is claimed is:
 1. A flexible tissue-modification device forremoving tissue from a patient, the device having an elongate body withan axial length, a width and a thickness, wherein the axial length isgreater than the width and the width is greater than the thickness, thedevice comprising: a flexible connector extending longitudinally alongthe axial length of the elongate body; a plurality of rigidtissue-cutting rungs that are flexibly connected by the connector,wherein each rung in the plurality of tissue-cutting rungs extends atleast partially across the width of the elongate body; at least onecutting edge on each of the tissue-cutting rungs; a plurality ofspacers, wherein each rung in the plurality of tissue-cutting rungs isseparated from an adjacent rung by a spacer, wherein the spacer forms anopening though the device between adjacent rungs that extends across thewidth of the elongate body; and a guidewire coupler attached to theconnector at a distal end of the device, wherein the guidewire couplerincludes a tapered distal end region that is configured to fit anenlarged proximal end of a guidewire so that the guidewire engages withthe guidewire coupler when pulled distally.
 2. The device of claim 1,wherein the plurality of tissue-cutting rungs comprises rungs havingdifferent configurations or sizes.
 3. The device of claim 1, wherein theconnector comprises at least one cable.
 4. The device of claim 1,further comprising at least one protective side guard extending alongthe axial length of the elongate body.
 5. The device of claim 1, whereinthe cutting edge projects from a surface of the rung.
 6. The device ofclaim 1, further comprising a tissue collection region in communicationwith the rung.
 7. The device of claim 1, wherein the opening through thedevice is configured to provide a passage between adjacent rungs.
 8. Thedevice of claim 1, wherein the spacer is a ferrule.
 9. The device ofclaim 1, wherein the plurality of rigid tissue-cutting rungs and theplurality of spacers are threaded on the connector.
 10. A flexibletissue-modification device for removing tissue from a patient, thedevice having an elongate body with an axial length, a width and athickness, wherein the axial length is greater than the width and thewidth is greater than the thickness, the device having an anterior,tissue-facing surface, the device comprising: a proximal handle; aflexible connector extending longitudinally along the axial length ofthe device from the handle; a first set of rigid tissue-cutting rungsthat are flexibly connected to the connector, wherein the first set oftissue-cutting rungs include at least one first cutting edge projectingfrom the anterior surface of and positioned between lateral edges ofeach rung of the first set of rigid tissue-cutting rungs and each firstcutting edge extends substantially perpendicular to the axial length; asecond set of rigid tissue-cutting rungs that are flexibly connected tothe connector, wherein the second set of tissue-cutting rungs include atleast one second cutting edge projecting from the anterior surface ofand extending along the axial length of a lateral edge of each rung ofthe second set of rigid tissue-cutting rungs, each second cutting edgeextending substantially along the axial length; and a guidewire couplerattached to the connector at a distal end of the device.
 11. The deviceof claim 10, wherein each second cutting edge is sized and configured tocut a strip of soft tissue.
 12. The device of claim 11, wherein eachsecond cutting edge includes a tombstone shaped edge.
 13. The device ofclaim 11, wherein the soft tissue is ligamentum flavum.
 14. The deviceof claim 1, further comprising a proximal handle attached to theconnector.
 15. The device of claim 1, wherein the connector comprises atleast two flexible elongate cables, wherein the cables extendsubstantially adjacent to each other from a proximal end region of thedevice to a distal end region of the device.
 16. The device of claim 1,wherein the plurality of rigid, tissue-cutting rungs are I-shaped suchthat the spacer is integral with the rung.
 17. A flexibletissue-modification device for removing tissue from a patient, thedevice having an elongate body with an axial length, a width and athickness, wherein the axial length is greater than the width and thewidth is greater than the thickness, the device comprising: a flexibleconnector comprising two lengths of cable extending adjacently along theaxial length of the device; a plurality of rigid, tissue-cutting rungsthat are connected to the lengths of cable, wherein each rung extends atleast partially across the width of the body between the two lengths ofcable and is separated from adjacent rungs by a spacer forming anopening though the device between adjacent rungs; a cutting edge on eachof the tissue-cutting rungs; and a guidewire coupler attached to theconnector at a distal end of the device, wherein the guidewire couplerincludes a tapered distal end region that is configured to fit anenlarged proximal end of a guidewire so that the guidewire engages withthe guidewire coupler when pulled distally.
 18. The device of claim 17,wherein the spacer is integral with the rung.
 19. The device of claim17, wherein the spacer is separate from the rung and positioned betweenadjacent rungs.